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<!DOCTYPE html><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1, maximum-scale=1, user-scalable=no"><meta http-equiv="Content-Language" content="en"><meta http-equiv="X-UA-Compatible" content="IE=edge"><title>functions.js</title><link href="../../../../dossier.css" rel="stylesheet" type="text/css"><header><div><form><div><input type="search" placeholder="Search" tabindex="1"></div></form></div></header><main><article class="srcfile"><h1>lib/goog/functions/functions.js</h1><div><table><tr><td><a id="l1"></a><a href="#l1">1</a><td>// Copyright 2008 The Closure Library Authors. All Rights Reserved.<tr><td><a id="l2"></a><a href="#l2">2</a><td>//<tr><td><a id="l3"></a><a href="#l3">3</a><td>// Licensed under the Apache License, Version 2.0 (the "License");<tr><td><a id="l4"></a><a href="#l4">4</a><td>// you may not use this file except in compliance with the License.<tr><td><a id="l5"></a><a href="#l5">5</a><td>// You may obtain a copy of the License at<tr><td><a id="l6"></a><a href="#l6">6</a><td>//<tr><td><a id="l7"></a><a href="#l7">7</a><td>// http://www.apache.org/licenses/LICENSE-2.0<tr><td><a id="l8"></a><a href="#l8">8</a><td>//<tr><td><a id="l9"></a><a href="#l9">9</a><td>// Unless required by applicable law or agreed to in writing, software<tr><td><a id="l10"></a><a href="#l10">10</a><td>// distributed under the License is distributed on an "AS-IS" BASIS,<tr><td><a id="l11"></a><a href="#l11">11</a><td>// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<tr><td><a id="l12"></a><a href="#l12">12</a><td>// See the License for the specific language governing permissions and<tr><td><a id="l13"></a><a href="#l13">13</a><td>// limitations under the License.<tr><td><a id="l14"></a><a href="#l14">14</a><td><tr><td><a id="l15"></a><a href="#l15">15</a><td>/**<tr><td><a id="l16"></a><a href="#l16">16</a><td> * @fileoverview Utilities for creating functions. Loosely inspired by the<tr><td><a id="l17"></a><a href="#l17">17</a><td> * java classes: http://goo.gl/GM0Hmu and http://goo.gl/6k7nI8.<tr><td><a id="l18"></a><a href="#l18">18</a><td> *<tr><td><a id="l19"></a><a href="#l19">19</a><td> * @author nicksantos@google.com (Nick Santos)<tr><td><a id="l20"></a><a href="#l20">20</a><td> */<tr><td><a id="l21"></a><a href="#l21">21</a><td><tr><td><a id="l22"></a><a href="#l22">22</a><td><tr><td><a id="l23"></a><a href="#l23">23</a><td>goog.provide('goog.functions');<tr><td><a id="l24"></a><a href="#l24">24</a><td><tr><td><a id="l25"></a><a href="#l25">25</a><td><tr><td><a id="l26"></a><a href="#l26">26</a><td>/**<tr><td><a id="l27"></a><a href="#l27">27</a><td> * Creates a function that always returns the same value.<tr><td><a id="l28"></a><a href="#l28">28</a><td> * @param {T} retValue The value to return.<tr><td><a id="l29"></a><a href="#l29">29</a><td> * @return {function():T} The new function.<tr><td><a id="l30"></a><a href="#l30">30</a><td> * @template T<tr><td><a id="l31"></a><a href="#l31">31</a><td> */<tr><td><a id="l32"></a><a href="#l32">32</a><td>goog.functions.constant = function(retValue) {<tr><td><a id="l33"></a><a href="#l33">33</a><td> return function() {<tr><td><a id="l34"></a><a href="#l34">34</a><td> return retValue;<tr><td><a id="l35"></a><a href="#l35">35</a><td> };<tr><td><a id="l36"></a><a href="#l36">36</a><td>};<tr><td><a id="l37"></a><a href="#l37">37</a><td><tr><td><a id="l38"></a><a href="#l38">38</a><td><tr><td><a id="l39"></a><a href="#l39">39</a><td>/**<tr><td><a id="l40"></a><a href="#l40">40</a><td> * Always returns false.<tr><td><a id="l41"></a><a href="#l41">41</a><td> * @type {function(...): boolean}<tr><td><a id="l42"></a><a href="#l42">42</a><td> */<tr><td><a id="l43"></a><a href="#l43">43</a><td>goog.functions.FALSE = goog.functions.constant(false);<tr><td><a id="l44"></a><a href="#l44">44</a><td><tr><td><a id="l45"></a><a href="#l45">45</a><td><tr><td><a id="l46"></a><a href="#l46">46</a><td>/**<tr><td><a id="l47"></a><a href="#l47">47</a><td> * Always returns true.<tr><td><a id="l48"></a><a href="#l48">48</a><td> * @type {function(...): boolean}<tr><td><a id="l49"></a><a href="#l49">49</a><td> */<tr><td><a id="l50"></a><a href="#l50">50</a><td>goog.functions.TRUE = goog.functions.constant(true);<tr><td><a id="l51"></a><a href="#l51">51</a><td><tr><td><a id="l52"></a><a href="#l52">52</a><td><tr><td><a id="l53"></a><a href="#l53">53</a><td>/**<tr><td><a id="l54"></a><a href="#l54">54</a><td> * Always returns NULL.<tr><td><a id="l55"></a><a href="#l55">55</a><td> * @type {function(...): null}<tr><td><a id="l56"></a><a href="#l56">56</a><td> */<tr><td><a id="l57"></a><a href="#l57">57</a><td>goog.functions.NULL = goog.functions.constant(null);<tr><td><a id="l58"></a><a href="#l58">58</a><td><tr><td><a id="l59"></a><a href="#l59">59</a><td><tr><td><a id="l60"></a><a href="#l60">60</a><td>/**<tr><td><a id="l61"></a><a href="#l61">61</a><td> * A simple function that returns the first argument of whatever is passed<tr><td><a id="l62"></a><a href="#l62">62</a><td> * into it.<tr><td><a id="l63"></a><a href="#l63">63</a><td> * @param {T=} opt_returnValue The single value that will be returned.<tr><td><a id="l64"></a><a href="#l64">64</a><td> * @param {...*} var_args Optional trailing arguments. These are ignored.<tr><td><a id="l65"></a><a href="#l65">65</a><td> * @return {T} The first argument passed in, or undefined if nothing was passed.<tr><td><a id="l66"></a><a href="#l66">66</a><td> * @template T<tr><td><a id="l67"></a><a href="#l67">67</a><td> */<tr><td><a id="l68"></a><a href="#l68">68</a><td>goog.functions.identity = function(opt_returnValue, var_args) {<tr><td><a id="l69"></a><a href="#l69">69</a><td> return opt_returnValue;<tr><td><a id="l70"></a><a href="#l70">70</a><td>};<tr><td><a id="l71"></a><a href="#l71">71</a><td><tr><td><a id="l72"></a><a href="#l72">72</a><td><tr><td><a id="l73"></a><a href="#l73">73</a><td>/**<tr><td><a id="l74"></a><a href="#l74">74</a><td> * Creates a function that always throws an error with the given message.<tr><td><a id="l75"></a><a href="#l75">75</a><td> * @param {string} message The error message.<tr><td><a id="l76"></a><a href="#l76">76</a><td> * @return {!Function} The error-throwing function.<tr><td><a id="l77"></a><a href="#l77">77</a><td> */<tr><td><a id="l78"></a><a href="#l78">78</a><td>goog.functions.error = function(message) {<tr><td><a id="l79"></a><a href="#l79">79</a><td> return function() {<tr><td><a id="l80"></a><a href="#l80">80</a><td> throw Error(message);<tr><td><a id="l81"></a><a href="#l81">81</a><td> };<tr><td><a id="l82"></a><a href="#l82">82</a><td>};<tr><td><a id="l83"></a><a href="#l83">83</a><td><tr><td><a id="l84"></a><a href="#l84">84</a><td><tr><td><a id="l85"></a><a href="#l85">85</a><td>/**<tr><td><a id="l86"></a><a href="#l86">86</a><td> * Creates a function that throws the given object.<tr><td><a id="l87"></a><a href="#l87">87</a><td> * @param {*} err An object to be thrown.<tr><td><a id="l88"></a><a href="#l88">88</a><td> * @return {!Function} The error-throwing function.<tr><td><a id="l89"></a><a href="#l89">89</a><td> */<tr><td><a id="l90"></a><a href="#l90">90</a><td>goog.functions.fail = function(err) {<tr><td><a id="l91"></a><a href="#l91">91</a><td> return function() {<tr><td><a id="l92"></a><a href="#l92">92</a><td> throw err;<tr><td><a id="l93"></a><a href="#l93">93</a><td> }<tr><td><a id="l94"></a><a href="#l94">94</a><td>};<tr><td><a id="l95"></a><a href="#l95">95</a><td><tr><td><a id="l96"></a><a href="#l96">96</a><td><tr><td><a id="l97"></a><a href="#l97">97</a><td>/**<tr><td><a id="l98"></a><a href="#l98">98</a><td> * Given a function, create a function that keeps opt_numArgs arguments and<tr><td><a id="l99"></a><a href="#l99">99</a><td> * silently discards all additional arguments.<tr><td><a id="l100"></a><a href="#l100">100</a><td> * @param {Function} f The original function.<tr><td><a id="l101"></a><a href="#l101">101</a><td> * @param {number=} opt_numArgs The number of arguments to keep. Defaults to 0.<tr><td><a id="l102"></a><a href="#l102">102</a><td> * @return {!Function} A version of f that only keeps the first opt_numArgs<tr><td><a id="l103"></a><a href="#l103">103</a><td> * arguments.<tr><td><a id="l104"></a><a href="#l104">104</a><td> */<tr><td><a id="l105"></a><a href="#l105">105</a><td>goog.functions.lock = function(f, opt_numArgs) {<tr><td><a id="l106"></a><a href="#l106">106</a><td> opt_numArgs = opt_numArgs || 0;<tr><td><a id="l107"></a><a href="#l107">107</a><td> return function() {<tr><td><a id="l108"></a><a href="#l108">108</a><td> return f.apply(this, Array.prototype.slice.call(arguments, 0, opt_numArgs));<tr><td><a id="l109"></a><a href="#l109">109</a><td> };<tr><td><a id="l110"></a><a href="#l110">110</a><td>};<tr><td><a id="l111"></a><a href="#l111">111</a><td><tr><td><a id="l112"></a><a href="#l112">112</a><td><tr><td><a id="l113"></a><a href="#l113">113</a><td>/**<tr><td><a id="l114"></a><a href="#l114">114</a><td> * Creates a function that returns its nth argument.<tr><td><a id="l115"></a><a href="#l115">115</a><td> * @param {number} n The position of the return argument.<tr><td><a id="l116"></a><a href="#l116">116</a><td> * @return {!Function} A new function.<tr><td><a id="l117"></a><a href="#l117">117</a><td> */<tr><td><a id="l118"></a><a href="#l118">118</a><td>goog.functions.nth = function(n) {<tr><td><a id="l119"></a><a href="#l119">119</a><td> return function() {<tr><td><a id="l120"></a><a href="#l120">120</a><td> return arguments[n];<tr><td><a id="l121"></a><a href="#l121">121</a><td> };<tr><td><a id="l122"></a><a href="#l122">122</a><td>};<tr><td><a id="l123"></a><a href="#l123">123</a><td><tr><td><a id="l124"></a><a href="#l124">124</a><td><tr><td><a id="l125"></a><a href="#l125">125</a><td>/**<tr><td><a id="l126"></a><a href="#l126">126</a><td> * Given a function, create a new function that swallows its return value<tr><td><a id="l127"></a><a href="#l127">127</a><td> * and replaces it with a new one.<tr><td><a id="l128"></a><a href="#l128">128</a><td> * @param {Function} f A function.<tr><td><a id="l129"></a><a href="#l129">129</a><td> * @param {T} retValue A new return value.<tr><td><a id="l130"></a><a href="#l130">130</a><td> * @return {function(...?):T} A new function.<tr><td><a id="l131"></a><a href="#l131">131</a><td> * @template T<tr><td><a id="l132"></a><a href="#l132">132</a><td> */<tr><td><a id="l133"></a><a href="#l133">133</a><td>goog.functions.withReturnValue = function(f, retValue) {<tr><td><a id="l134"></a><a href="#l134">134</a><td> return goog.functions.sequence(f, goog.functions.constant(retValue));<tr><td><a id="l135"></a><a href="#l135">135</a><td>};<tr><td><a id="l136"></a><a href="#l136">136</a><td><tr><td><a id="l137"></a><a href="#l137">137</a><td><tr><td><a id="l138"></a><a href="#l138">138</a><td>/**<tr><td><a id="l139"></a><a href="#l139">139</a><td> * Creates a function that returns whether its arguement equals the given value.<tr><td><a id="l140"></a><a href="#l140">140</a><td> *<tr><td><a id="l141"></a><a href="#l141">141</a><td> * Example:<tr><td><a id="l142"></a><a href="#l142">142</a><td> * var key = goog.object.findKey(obj, goog.functions.equalTo('needle'));<tr><td><a id="l143"></a><a href="#l143">143</a><td> *<tr><td><a id="l144"></a><a href="#l144">144</a><td> * @param {*} value The value to compare to.<tr><td><a id="l145"></a><a href="#l145">145</a><td> * @param {boolean=} opt_useLooseComparison Whether to use a loose (==)<tr><td><a id="l146"></a><a href="#l146">146</a><td> * comparison rather than a strict (===) one. Defaults to false.<tr><td><a id="l147"></a><a href="#l147">147</a><td> * @return {function(*):boolean} The new function.<tr><td><a id="l148"></a><a href="#l148">148</a><td> */<tr><td><a id="l149"></a><a href="#l149">149</a><td>goog.functions.equalTo = function(value, opt_useLooseComparison) {<tr><td><a id="l150"></a><a href="#l150">150</a><td> return function(other) {<tr><td><a id="l151"></a><a href="#l151">151</a><td> return opt_useLooseComparison ? (value == other) : (value === other);<tr><td><a id="l152"></a><a href="#l152">152</a><td> };<tr><td><a id="l153"></a><a href="#l153">153</a><td>};<tr><td><a id="l154"></a><a href="#l154">154</a><td><tr><td><a id="l155"></a><a href="#l155">155</a><td><tr><td><a id="l156"></a><a href="#l156">156</a><td>/**<tr><td><a id="l157"></a><a href="#l157">157</a><td> * Creates the composition of the functions passed in.<tr><td><a id="l158"></a><a href="#l158">158</a><td> * For example, (goog.functions.compose(f, g))(a) is equivalent to f(g(a)).<tr><td><a id="l159"></a><a href="#l159">159</a><td> * @param {function(...?):T} fn The final function.<tr><td><a id="l160"></a><a href="#l160">160</a><td> * @param {...Function} var_args A list of functions.<tr><td><a id="l161"></a><a href="#l161">161</a><td> * @return {function(...?):T} The composition of all inputs.<tr><td><a id="l162"></a><a href="#l162">162</a><td> * @template T<tr><td><a id="l163"></a><a href="#l163">163</a><td> */<tr><td><a id="l164"></a><a href="#l164">164</a><td>goog.functions.compose = function(fn, var_args) {<tr><td><a id="l165"></a><a href="#l165">165</a><td> var functions = arguments;<tr><td><a id="l166"></a><a href="#l166">166</a><td> var length = functions.length;<tr><td><a id="l167"></a><a href="#l167">167</a><td> return function() {<tr><td><a id="l168"></a><a href="#l168">168</a><td> var result;<tr><td><a id="l169"></a><a href="#l169">169</a><td> if (length) {<tr><td><a id="l170"></a><a href="#l170">170</a><td> result = functions[length - 1].apply(this, arguments);<tr><td><a id="l171"></a><a href="#l171">171</a><td> }<tr><td><a id="l172"></a><a href="#l172">172</a><td><tr><td><a id="l173"></a><a href="#l173">173</a><td> for (var i = length - 2; i >= 0; i--) {<tr><td><a id="l174"></a><a href="#l174">174</a><td> result = functions[i].call(this, result);<tr><td><a id="l175"></a><a href="#l175">175</a><td> }<tr><td><a id="l176"></a><a href="#l176">176</a><td> return result;<tr><td><a id="l177"></a><a href="#l177">177</a><td> };<tr><td><a id="l178"></a><a href="#l178">178</a><td>};<tr><td><a id="l179"></a><a href="#l179">179</a><td><tr><td><a id="l180"></a><a href="#l180">180</a><td><tr><td><a id="l181"></a><a href="#l181">181</a><td>/**<tr><td><a id="l182"></a><a href="#l182">182</a><td> * Creates a function that calls the functions passed in in sequence, and<tr><td><a id="l183"></a><a href="#l183">183</a><td> * returns the value of the last function. For example,<tr><td><a id="l184"></a><a href="#l184">184</a><td> * (goog.functions.sequence(f, g))(x) is equivalent to f(x),g(x).<tr><td><a id="l185"></a><a href="#l185">185</a><td> * @param {...Function} var_args A list of functions.<tr><td><a id="l186"></a><a href="#l186">186</a><td> * @return {!Function} A function that calls all inputs in sequence.<tr><td><a id="l187"></a><a href="#l187">187</a><td> */<tr><td><a id="l188"></a><a href="#l188">188</a><td>goog.functions.sequence = function(var_args) {<tr><td><a id="l189"></a><a href="#l189">189</a><td> var functions = arguments;<tr><td><a id="l190"></a><a href="#l190">190</a><td> var length = functions.length;<tr><td><a id="l191"></a><a href="#l191">191</a><td> return function() {<tr><td><a id="l192"></a><a href="#l192">192</a><td> var result;<tr><td><a id="l193"></a><a href="#l193">193</a><td> for (var i = 0; i < length; i++) {<tr><td><a id="l194"></a><a href="#l194">194</a><td> result = functions[i].apply(this, arguments);<tr><td><a id="l195"></a><a href="#l195">195</a><td> }<tr><td><a id="l196"></a><a href="#l196">196</a><td> return result;<tr><td><a id="l197"></a><a href="#l197">197</a><td> };<tr><td><a id="l198"></a><a href="#l198">198</a><td>};<tr><td><a id="l199"></a><a href="#l199">199</a><td><tr><td><a id="l200"></a><a href="#l200">200</a><td><tr><td><a id="l201"></a><a href="#l201">201</a><td>/**<tr><td><a id="l202"></a><a href="#l202">202</a><td> * Creates a function that returns true if each of its components evaluates<tr><td><a id="l203"></a><a href="#l203">203</a><td> * to true. The components are evaluated in order, and the evaluation will be<tr><td><a id="l204"></a><a href="#l204">204</a><td> * short-circuited as soon as a function returns false.<tr><td><a id="l205"></a><a href="#l205">205</a><td> * For example, (goog.functions.and(f, g))(x) is equivalent to f(x) && g(x).<tr><td><a id="l206"></a><a href="#l206">206</a><td> * @param {...Function} var_args A list of functions.<tr><td><a id="l207"></a><a href="#l207">207</a><td> * @return {function(...?):boolean} A function that ANDs its component<tr><td><a id="l208"></a><a href="#l208">208</a><td> * functions.<tr><td><a id="l209"></a><a href="#l209">209</a><td> */<tr><td><a id="l210"></a><a href="#l210">210</a><td>goog.functions.and = function(var_args) {<tr><td><a id="l211"></a><a href="#l211">211</a><td> var functions = arguments;<tr><td><a id="l212"></a><a href="#l212">212</a><td> var length = functions.length;<tr><td><a id="l213"></a><a href="#l213">213</a><td> return function() {<tr><td><a id="l214"></a><a href="#l214">214</a><td> for (var i = 0; i < length; i++) {<tr><td><a id="l215"></a><a href="#l215">215</a><td> if (!functions[i].apply(this, arguments)) {<tr><td><a id="l216"></a><a href="#l216">216</a><td> return false;<tr><td><a id="l217"></a><a href="#l217">217</a><td> }<tr><td><a id="l218"></a><a href="#l218">218</a><td> }<tr><td><a id="l219"></a><a href="#l219">219</a><td> return true;<tr><td><a id="l220"></a><a href="#l220">220</a><td> };<tr><td><a id="l221"></a><a href="#l221">221</a><td>};<tr><td><a id="l222"></a><a href="#l222">222</a><td><tr><td><a id="l223"></a><a href="#l223">223</a><td><tr><td><a id="l224"></a><a href="#l224">224</a><td>/**<tr><td><a id="l225"></a><a href="#l225">225</a><td> * Creates a function that returns true if any of its components evaluates<tr><td><a id="l226"></a><a href="#l226">226</a><td> * to true. The components are evaluated in order, and the evaluation will be<tr><td><a id="l227"></a><a href="#l227">227</a><td> * short-circuited as soon as a function returns true.<tr><td><a id="l228"></a><a href="#l228">228</a><td> * For example, (goog.functions.or(f, g))(x) is equivalent to f(x) || g(x).<tr><td><a id="l229"></a><a href="#l229">229</a><td> * @param {...Function} var_args A list of functions.<tr><td><a id="l230"></a><a href="#l230">230</a><td> * @return {function(...?):boolean} A function that ORs its component<tr><td><a id="l231"></a><a href="#l231">231</a><td> * functions.<tr><td><a id="l232"></a><a href="#l232">232</a><td> */<tr><td><a id="l233"></a><a href="#l233">233</a><td>goog.functions.or = function(var_args) {<tr><td><a id="l234"></a><a href="#l234">234</a><td> var functions = arguments;<tr><td><a id="l235"></a><a href="#l235">235</a><td> var length = functions.length;<tr><td><a id="l236"></a><a href="#l236">236</a><td> return function() {<tr><td><a id="l237"></a><a href="#l237">237</a><td> for (var i = 0; i < length; i++) {<tr><td><a id="l238"></a><a href="#l238">238</a><td> if (functions[i].apply(this, arguments)) {<tr><td><a id="l239"></a><a href="#l239">239</a><td> return true;<tr><td><a id="l240"></a><a href="#l240">240</a><td> }<tr><td><a id="l241"></a><a href="#l241">241</a><td> }<tr><td><a id="l242"></a><a href="#l242">242</a><td> return false;<tr><td><a id="l243"></a><a href="#l243">243</a><td> };<tr><td><a id="l244"></a><a href="#l244">244</a><td>};<tr><td><a id="l245"></a><a href="#l245">245</a><td><tr><td><a id="l246"></a><a href="#l246">246</a><td><tr><td><a id="l247"></a><a href="#l247">247</a><td>/**<tr><td><a id="l248"></a><a href="#l248">248</a><td> * Creates a function that returns the Boolean opposite of a provided function.<tr><td><a id="l249"></a><a href="#l249">249</a><td> * For example, (goog.functions.not(f))(x) is equivalent to !f(x).<tr><td><a id="l250"></a><a href="#l250">250</a><td> * @param {!Function} f The original function.<tr><td><a id="l251"></a><a href="#l251">251</a><td> * @return {function(...?):boolean} A function that delegates to f and returns<tr><td><a id="l252"></a><a href="#l252">252</a><td> * opposite.<tr><td><a id="l253"></a><a href="#l253">253</a><td> */<tr><td><a id="l254"></a><a href="#l254">254</a><td>goog.functions.not = function(f) {<tr><td><a id="l255"></a><a href="#l255">255</a><td> return function() {<tr><td><a id="l256"></a><a href="#l256">256</a><td> return !f.apply(this, arguments);<tr><td><a id="l257"></a><a href="#l257">257</a><td> };<tr><td><a id="l258"></a><a href="#l258">258</a><td>};<tr><td><a id="l259"></a><a href="#l259">259</a><td><tr><td><a id="l260"></a><a href="#l260">260</a><td><tr><td><a id="l261"></a><a href="#l261">261</a><td>/**<tr><td><a id="l262"></a><a href="#l262">262</a><td> * Generic factory function to construct an object given the constructor<tr><td><a id="l263"></a><a href="#l263">263</a><td> * and the arguments. Intended to be bound to create object factories.<tr><td><a id="l264"></a><a href="#l264">264</a><td> *<tr><td><a id="l265"></a><a href="#l265">265</a><td> * Example:<tr><td><a id="l266"></a><a href="#l266">266</a><td> *<tr><td><a id="l267"></a><a href="#l267">267</a><td> * var factory = goog.partial(goog.functions.create, Class);<tr><td><a id="l268"></a><a href="#l268">268</a><td> *<tr><td><a id="l269"></a><a href="#l269">269</a><td> * @param {function(new:T, ...)} constructor The constructor for the Object.<tr><td><a id="l270"></a><a href="#l270">270</a><td> * @param {...*} var_args The arguments to be passed to the constructor.<tr><td><a id="l271"></a><a href="#l271">271</a><td> * @return {T} A new instance of the class given in {@code constructor}.<tr><td><a id="l272"></a><a href="#l272">272</a><td> * @template T<tr><td><a id="l273"></a><a href="#l273">273</a><td> */<tr><td><a id="l274"></a><a href="#l274">274</a><td>goog.functions.create = function(constructor, var_args) {<tr><td><a id="l275"></a><a href="#l275">275</a><td> /**<tr><td><a id="l276"></a><a href="#l276">276</a><td> * @constructor<tr><td><a id="l277"></a><a href="#l277">277</a><td> * @final<tr><td><a id="l278"></a><a href="#l278">278</a><td> */<tr><td><a id="l279"></a><a href="#l279">279</a><td> var temp = function() {};<tr><td><a id="l280"></a><a href="#l280">280</a><td> temp.prototype = constructor.prototype;<tr><td><a id="l281"></a><a href="#l281">281</a><td><tr><td><a id="l282"></a><a href="#l282">282</a><td> // obj will have constructor's prototype in its chain and<tr><td><a id="l283"></a><a href="#l283">283</a><td> // 'obj instanceof constructor' will be true.<tr><td><a id="l284"></a><a href="#l284">284</a><td> var obj = new temp();<tr><td><a id="l285"></a><a href="#l285">285</a><td><tr><td><a id="l286"></a><a href="#l286">286</a><td> // obj is initialized by constructor.<tr><td><a id="l287"></a><a href="#l287">287</a><td> // arguments is only array-like so lacks shift(), but can be used with<tr><td><a id="l288"></a><a href="#l288">288</a><td> // the Array prototype function.<tr><td><a id="l289"></a><a href="#l289">289</a><td> constructor.apply(obj, Array.prototype.slice.call(arguments, 1));<tr><td><a id="l290"></a><a href="#l290">290</a><td> return obj;<tr><td><a id="l291"></a><a href="#l291">291</a><td>};<tr><td><a id="l292"></a><a href="#l292">292</a><td><tr><td><a id="l293"></a><a href="#l293">293</a><td><tr><td><a id="l294"></a><a href="#l294">294</a><td>/**<tr><td><a id="l295"></a><a href="#l295">295</a><td> * @define {boolean} Whether the return value cache should be used.<tr><td><a id="l296"></a><a href="#l296">296</a><td> * This should only be used to disable caches when testing.<tr><td><a id="l297"></a><a href="#l297">297</a><td> */<tr><td><a id="l298"></a><a href="#l298">298</a><td>goog.define('goog.functions.CACHE_RETURN_VALUE', true);<tr><td><a id="l299"></a><a href="#l299">299</a><td><tr><td><a id="l300"></a><a href="#l300">300</a><td><tr><td><a id="l301"></a><a href="#l301">301</a><td>/**<tr><td><a id="l302"></a><a href="#l302">302</a><td> * Gives a wrapper function that caches the return value of a parameterless<tr><td><a id="l303"></a><a href="#l303">303</a><td> * function when first called.<tr><td><a id="l304"></a><a href="#l304">304</a><td> *<tr><td><a id="l305"></a><a href="#l305">305</a><td> * When called for the first time, the given function is called and its<tr><td><a id="l306"></a><a href="#l306">306</a><td> * return value is cached (thus this is only appropriate for idempotent<tr><td><a id="l307"></a><a href="#l307">307</a><td> * functions). Subsequent calls will return the cached return value. This<tr><td><a id="l308"></a><a href="#l308">308</a><td> * allows the evaluation of expensive functions to be delayed until first used.<tr><td><a id="l309"></a><a href="#l309">309</a><td> *<tr><td><a id="l310"></a><a href="#l310">310</a><td> * To cache the return values of functions with parameters, see goog.memoize.<tr><td><a id="l311"></a><a href="#l311">311</a><td> *<tr><td><a id="l312"></a><a href="#l312">312</a><td> * @param {!function():T} fn A function to lazily evaluate.<tr><td><a id="l313"></a><a href="#l313">313</a><td> * @return {!function():T} A wrapped version the function.<tr><td><a id="l314"></a><a href="#l314">314</a><td> * @template T<tr><td><a id="l315"></a><a href="#l315">315</a><td> */<tr><td><a id="l316"></a><a href="#l316">316</a><td>goog.functions.cacheReturnValue = function(fn) {<tr><td><a id="l317"></a><a href="#l317">317</a><td> var called = false;<tr><td><a id="l318"></a><a href="#l318">318</a><td> var value;<tr><td><a id="l319"></a><a href="#l319">319</a><td><tr><td><a id="l320"></a><a href="#l320">320</a><td> return function() {<tr><td><a id="l321"></a><a href="#l321">321</a><td> if (!goog.functions.CACHE_RETURN_VALUE) {<tr><td><a id="l322"></a><a href="#l322">322</a><td> return fn();<tr><td><a id="l323"></a><a href="#l323">323</a><td> }<tr><td><a id="l324"></a><a href="#l324">324</a><td><tr><td><a id="l325"></a><a href="#l325">325</a><td> if (!called) {<tr><td><a id="l326"></a><a href="#l326">326</a><td> value = fn();<tr><td><a id="l327"></a><a href="#l327">327</a><td> called = true;<tr><td><a id="l328"></a><a href="#l328">328</a><td> }<tr><td><a id="l329"></a><a href="#l329">329</a><td><tr><td><a id="l330"></a><a href="#l330">330</a><td> return value;<tr><td><a id="l331"></a><a href="#l331">331</a><td> }<tr><td><a id="l332"></a><a href="#l332">332</a><td>};<tr><td><a id="l333"></a><a href="#l333">333</a><td><tr><td><a id="l334"></a><a href="#l334">334</a><td><tr><td><a id="l335"></a><a href="#l335">335</a><td>/**<tr><td><a id="l336"></a><a href="#l336">336</a><td> * Wraps a function to allow it to be called, at most, once. All<tr><td><a id="l337"></a><a href="#l337">337</a><td> * additional calls are no-ops.<tr><td><a id="l338"></a><a href="#l338">338</a><td> *<tr><td><a id="l339"></a><a href="#l339">339</a><td> * This is particularly useful for initialization functions<tr><td><a id="l340"></a><a href="#l340">340</a><td> * that should be called, at most, once.<tr><td><a id="l341"></a><a href="#l341">341</a><td> *<tr><td><a id="l342"></a><a href="#l342">342</a><td> * @param {function():*} f Function to call.<tr><td><a id="l343"></a><a href="#l343">343</a><td> * @return {function():undefined} Wrapped function.<tr><td><a id="l344"></a><a href="#l344">344</a><td> */<tr><td><a id="l345"></a><a href="#l345">345</a><td>goog.functions.once = function(f) {<tr><td><a id="l346"></a><a href="#l346">346</a><td> // Keep a reference to the function that we null out when we're done with<tr><td><a id="l347"></a><a href="#l347">347</a><td> // it -- that way, the function can be GC'd when we're done with it.<tr><td><a id="l348"></a><a href="#l348">348</a><td> var inner = f;<tr><td><a id="l349"></a><a href="#l349">349</a><td> return function() {<tr><td><a id="l350"></a><a href="#l350">350</a><td> if (inner) {<tr><td><a id="l351"></a><a href="#l351">351</a><td> var tmp = inner;<tr><td><a id="l352"></a><a href="#l352">352</a><td> inner = null;<tr><td><a id="l353"></a><a href="#l353">353</a><td> tmp();<tr><td><a id="l354"></a><a href="#l354">354</a><td> }<tr><td><a id="l355"></a><a href="#l355">355</a><td> };<tr><td><a id="l356"></a><a href="#l356">356</a><td>};<tr><td><a id="l357"></a><a href="#l357">357</a><td><tr><td><a id="l358"></a><a href="#l358">358</a><td><tr><td><a id="l359"></a><a href="#l359">359</a><td>/**<tr><td><a id="l360"></a><a href="#l360">360</a><td> * Wraps a function to allow it to be called, at most, once for each sequence of<tr><td><a id="l361"></a><a href="#l361">361</a><td> * calls fired repeatedly so long as they are fired less than a specified<tr><td><a id="l362"></a><a href="#l362">362</a><td> * interval apart (in milliseconds). Whether it receives one signal or multiple,<tr><td><a id="l363"></a><a href="#l363">363</a><td> * it will always wait until a full interval has elapsed since the last signal<tr><td><a id="l364"></a><a href="#l364">364</a><td> * before performing the action, passing the arguments from the last call of the<tr><td><a id="l365"></a><a href="#l365">365</a><td> * debouncing decorator into the decorated function.<tr><td><a id="l366"></a><a href="#l366">366</a><td> *<tr><td><a id="l367"></a><a href="#l367">367</a><td> * This is particularly useful for bulking up repeated user actions (e.g. only<tr><td><a id="l368"></a><a href="#l368">368</a><td> * refreshing a view once a user finishes typing rather than updating with every<tr><td><a id="l369"></a><a href="#l369">369</a><td> * keystroke). For more stateful debouncing with support for pausing, resuming,<tr><td><a id="l370"></a><a href="#l370">370</a><td> * and canceling debounced actions, use {@code goog.async.Debouncer}.<tr><td><a id="l371"></a><a href="#l371">371</a><td> *<tr><td><a id="l372"></a><a href="#l372">372</a><td> * @param {function(this:SCOPE, ...?)} f Function to call.<tr><td><a id="l373"></a><a href="#l373">373</a><td> * @param {number} interval Interval over which to debounce. The function will<tr><td><a id="l374"></a><a href="#l374">374</a><td> * only be called after the full interval has elapsed since the last call.<tr><td><a id="l375"></a><a href="#l375">375</a><td> * @param {SCOPE=} opt_scope Object in whose scope to call the function.<tr><td><a id="l376"></a><a href="#l376">376</a><td> * @return {function(...?): undefined} Wrapped function.<tr><td><a id="l377"></a><a href="#l377">377</a><td> * @template SCOPE<tr><td><a id="l378"></a><a href="#l378">378</a><td> */<tr><td><a id="l379"></a><a href="#l379">379</a><td>goog.functions.debounce = function(f, interval, opt_scope) {<tr><td><a id="l380"></a><a href="#l380">380</a><td> if (opt_scope) {<tr><td><a id="l381"></a><a href="#l381">381</a><td> f = goog.bind(f, opt_scope);<tr><td><a id="l382"></a><a href="#l382">382</a><td> }<tr><td><a id="l383"></a><a href="#l383">383</a><td> var timeout = null;<tr><td><a id="l384"></a><a href="#l384">384</a><td> return /** @type {function(...?)} */ (function(var_args) {<tr><td><a id="l385"></a><a href="#l385">385</a><td> goog.global.clearTimeout(timeout);<tr><td><a id="l386"></a><a href="#l386">386</a><td> var args = arguments;<tr><td><a id="l387"></a><a href="#l387">387</a><td> timeout = goog.global.setTimeout(function() {<tr><td><a id="l388"></a><a href="#l388">388</a><td> f.apply(null, args);<tr><td><a id="l389"></a><a href="#l389">389</a><td> }, interval);<tr><td><a id="l390"></a><a href="#l390">390</a><td> });<tr><td><a id="l391"></a><a href="#l391">391</a><td>};<tr><td><a id="l392"></a><a href="#l392">392</a><td><tr><td><a id="l393"></a><a href="#l393">393</a><td><tr><td><a id="l394"></a><a href="#l394">394</a><td>/**<tr><td><a id="l395"></a><a href="#l395">395</a><td> * Wraps a function to allow it to be called, at most, once per interval<tr><td><a id="l396"></a><a href="#l396">396</a><td> * (specified in milliseconds). If it is called multiple times while it is<tr><td><a id="l397"></a><a href="#l397">397</a><td> * waiting, it will only perform the action once at the end of the interval,<tr><td><a id="l398"></a><a href="#l398">398</a><td> * passing the arguments from the last call of the throttling decorator into the<tr><td><a id="l399"></a><a href="#l399">399</a><td> * decorated function.<tr><td><a id="l400"></a><a href="#l400">400</a><td> *<tr><td><a id="l401"></a><a href="#l401">401</a><td> * This is particularly useful for limiting repeated user requests (e.g.<tr><td><a id="l402"></a><a href="#l402">402</a><td> * preventing a user from spamming a server with frequent view refreshes). For<tr><td><a id="l403"></a><a href="#l403">403</a><td> * more stateful throttling with support for pausing, resuming, and canceling<tr><td><a id="l404"></a><a href="#l404">404</a><td> * throttled actions, use {@code goog.async.Throttle}.<tr><td><a id="l405"></a><a href="#l405">405</a><td> *<tr><td><a id="l406"></a><a href="#l406">406</a><td> * @param {function(this:SCOPE, ...?)} f Function to call.<tr><td><a id="l407"></a><a href="#l407">407</a><td> * @param {number} interval Interval over which to throttle. The function can<tr><td><a id="l408"></a><a href="#l408">408</a><td> * only be called once per interval.<tr><td><a id="l409"></a><a href="#l409">409</a><td> * @param {SCOPE=} opt_scope Object in whose scope to call the function.<tr><td><a id="l410"></a><a href="#l410">410</a><td> * @return {function(...?): undefined} Wrapped function.<tr><td><a id="l411"></a><a href="#l411">411</a><td> * @template SCOPE<tr><td><a id="l412"></a><a href="#l412">412</a><td> */<tr><td><a id="l413"></a><a href="#l413">413</a><td>goog.functions.throttle = function(f, interval, opt_scope) {<tr><td><a id="l414"></a><a href="#l414">414</a><td> if (opt_scope) {<tr><td><a id="l415"></a><a href="#l415">415</a><td> f = goog.bind(f, opt_scope);<tr><td><a id="l416"></a><a href="#l416">416</a><td> }<tr><td><a id="l417"></a><a href="#l417">417</a><td> var timeout = null;<tr><td><a id="l418"></a><a href="#l418">418</a><td> var shouldFire = false;<tr><td><a id="l419"></a><a href="#l419">419</a><td> var args = [];<tr><td><a id="l420"></a><a href="#l420">420</a><td><tr><td><a id="l421"></a><a href="#l421">421</a><td> var handleTimeout = function() {<tr><td><a id="l422"></a><a href="#l422">422</a><td> timeout = null;<tr><td><a id="l423"></a><a href="#l423">423</a><td> if (shouldFire) {<tr><td><a id="l424"></a><a href="#l424">424</a><td> shouldFire = false;<tr><td><a id="l425"></a><a href="#l425">425</a><td> fire();<tr><td><a id="l426"></a><a href="#l426">426</a><td> }<tr><td><a id="l427"></a><a href="#l427">427</a><td> };<tr><td><a id="l428"></a><a href="#l428">428</a><td><tr><td><a id="l429"></a><a href="#l429">429</a><td> var fire = function() {<tr><td><a id="l430"></a><a href="#l430">430</a><td> timeout = goog.global.setTimeout(handleTimeout, interval);<tr><td><a id="l431"></a><a href="#l431">431</a><td> f.apply(null, args);<tr><td><a id="l432"></a><a href="#l432">432</a><td> };<tr><td><a id="l433"></a><a href="#l433">433</a><td><tr><td><a id="l434"></a><a href="#l434">434</a><td> return /** @type {function(...?)} */ (function(var_args) {<tr><td><a id="l435"></a><a href="#l435">435</a><td> args = arguments;<tr><td><a id="l436"></a><a href="#l436">436</a><td> if (!timeout) {<tr><td><a id="l437"></a><a href="#l437">437</a><td> fire();<tr><td><a id="l438"></a><a href="#l438">438</a><td> } else {<tr><td><a id="l439"></a><a href="#l439">439</a><td> shouldFire = true;<tr><td><a id="l440"></a><a href="#l440">440</a><td> }<tr><td><a id="l441"></a><a href="#l441">441</a><td> });<tr><td><a id="l442"></a><a href="#l442">442</a><td>};</table></div></article><nav><h3><a href="../../../../index.html" tabindex="2">Overview</a></h3><div><input type="checkbox" id="nav-modules" checked/><label for="nav-modules"><h3><span class="selectable" tabindex="2">Modules</span></h3></label><div id="nav-modules-view"></div></div><div><input type="checkbox" id="nav-types" checked/><label for="nav-types"><h3><span class="selectable" tabindex="2">Types</span></h3></label><div id="nav-types-view"></div></div><h3><a href="../../../../Changes.html" tabindex="2">Changes</a></h3></nav></main><footer><div><a href="https://github.com/jleyba/js-dossier">Generated by dossier</a></div></footer><script src="../../../../types.js"></script><script src="../../../../dossier.js"></script>