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<meta charset="UTF-8"><meta http-equiv="Content-Language" content="en" /><title>nexttick.js</title><link href="../../../../dossier.css" rel="stylesheet" type="text/css"><div id="main-wrapper"><input type="checkbox" id="sidenav-toggle" /><main><header><h1>lib/goog/async/nexttick.js</h1></header><pre><table class="srcfile"><tbody><tr><td><a name="l1" href="#l1">1</a><td>// Copyright 2013 The Closure Library Authors. All Rights Reserved.<tr><td><a name="l2" href="#l2">2</a><td>//<tr><td><a name="l3" href="#l3">3</a><td>// Licensed under the Apache License, Version 2.0 (the "License");<tr><td><a name="l4" href="#l4">4</a><td>// you may not use this file except in compliance with the License.<tr><td><a name="l5" href="#l5">5</a><td>// You may obtain a copy of the License at<tr><td><a name="l6" href="#l6">6</a><td>//<tr><td><a name="l7" href="#l7">7</a><td>// http://www.apache.org/licenses/LICENSE-2.0<tr><td><a name="l8" href="#l8">8</a><td>//<tr><td><a name="l9" href="#l9">9</a><td>// Unless required by applicable law or agreed to in writing, software<tr><td><a name="l10" href="#l10">10</a><td>// distributed under the License is distributed on an "AS-IS" BASIS,<tr><td><a name="l11" href="#l11">11</a><td>// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<tr><td><a name="l12" href="#l12">12</a><td>// See the License for the specific language governing permissions and<tr><td><a name="l13" href="#l13">13</a><td>// limitations under the License.<tr><td><a name="l14" href="#l14">14</a><td><tr><td><a name="l15" href="#l15">15</a><td>/**<tr><td><a name="l16" href="#l16">16</a><td> * @fileoverview Provides a function to schedule running a function as soon<tr><td><a name="l17" href="#l17">17</a><td> * as possible after the current JS execution stops and yields to the event<tr><td><a name="l18" href="#l18">18</a><td> * loop.<tr><td><a name="l19" href="#l19">19</a><td> *<tr><td><a name="l20" href="#l20">20</a><td> */<tr><td><a name="l21" href="#l21">21</a><td><tr><td><a name="l22" href="#l22">22</a><td>goog.provide('goog.async.nextTick');<tr><td><a name="l23" href="#l23">23</a><td>goog.provide('goog.async.throwException');<tr><td><a name="l24" href="#l24">24</a><td><tr><td><a name="l25" href="#l25">25</a><td>goog.require('goog.debug.entryPointRegistry');<tr><td><a name="l26" href="#l26">26</a><td>goog.require('goog.functions');<tr><td><a name="l27" href="#l27">27</a><td>goog.require('goog.labs.userAgent.browser');<tr><td><a name="l28" href="#l28">28</a><td><tr><td><a name="l29" href="#l29">29</a><td><tr><td><a name="l30" href="#l30">30</a><td>/**<tr><td><a name="l31" href="#l31">31</a><td> * Throw an item without interrupting the current execution context. For<tr><td><a name="l32" href="#l32">32</a><td> * example, if processing a group of items in a loop, sometimes it is useful<tr><td><a name="l33" href="#l33">33</a><td> * to report an error while still allowing the rest of the batch to be<tr><td><a name="l34" href="#l34">34</a><td> * processed.<tr><td><a name="l35" href="#l35">35</a><td> * @param {*} exception<tr><td><a name="l36" href="#l36">36</a><td> */<tr><td><a name="l37" href="#l37">37</a><td>goog.async.throwException = function(exception) {<tr><td><a name="l38" href="#l38">38</a><td> // Each throw needs to be in its own context.<tr><td><a name="l39" href="#l39">39</a><td> goog.global.setTimeout(function() { throw exception; }, 0);<tr><td><a name="l40" href="#l40">40</a><td>};<tr><td><a name="l41" href="#l41">41</a><td><tr><td><a name="l42" href="#l42">42</a><td><tr><td><a name="l43" href="#l43">43</a><td>/**<tr><td><a name="l44" href="#l44">44</a><td> * Fires the provided callbacks as soon as possible after the current JS<tr><td><a name="l45" href="#l45">45</a><td> * execution context. setTimeout(…, 0) takes at least 4ms when called from<tr><td><a name="l46" href="#l46">46</a><td> * within another setTimeout(…, 0) for legacy reasons.<tr><td><a name="l47" href="#l47">47</a><td> *<tr><td><a name="l48" href="#l48">48</a><td> * This will not schedule the callback as a microtask (i.e. a task that can<tr><td><a name="l49" href="#l49">49</a><td> * preempt user input or networking callbacks). It is meant to emulate what<tr><td><a name="l50" href="#l50">50</a><td> * setTimeout(_, 0) would do if it were not throttled. If you desire microtask<tr><td><a name="l51" href="#l51">51</a><td> * behavior, use {@see goog.Promise} instead.<tr><td><a name="l52" href="#l52">52</a><td> *<tr><td><a name="l53" href="#l53">53</a><td> * @param {function(this:SCOPE)} callback Callback function to fire as soon as<tr><td><a name="l54" href="#l54">54</a><td> * possible.<tr><td><a name="l55" href="#l55">55</a><td> * @param {SCOPE=} opt_context Object in whose scope to call the listener.<tr><td><a name="l56" href="#l56">56</a><td> * @template SCOPE<tr><td><a name="l57" href="#l57">57</a><td> */<tr><td><a name="l58" href="#l58">58</a><td>goog.async.nextTick = function(callback, opt_context) {<tr><td><a name="l59" href="#l59">59</a><td> var cb = callback;<tr><td><a name="l60" href="#l60">60</a><td> if (opt_context) {<tr><td><a name="l61" href="#l61">61</a><td> cb = goog.bind(callback, opt_context);<tr><td><a name="l62" href="#l62">62</a><td> }<tr><td><a name="l63" href="#l63">63</a><td> cb = goog.async.nextTick.wrapCallback_(cb);<tr><td><a name="l64" href="#l64">64</a><td> // window.setImmediate was introduced and currently only supported by IE10+,<tr><td><a name="l65" href="#l65">65</a><td> // but due to a bug in the implementation it is not guaranteed that<tr><td><a name="l66" href="#l66">66</a><td> // setImmediate is faster than setTimeout nor that setImmediate N is before<tr><td><a name="l67" href="#l67">67</a><td> // setImmediate N+1. That is why we do not use the native version if<tr><td><a name="l68" href="#l68">68</a><td> // available. We do, however, call setImmediate if it is a normal function<tr><td><a name="l69" href="#l69">69</a><td> // because that indicates that it has been replaced by goog.testing.MockClock<tr><td><a name="l70" href="#l70">70</a><td> // which we do want to support.<tr><td><a name="l71" href="#l71">71</a><td> // See<tr><td><a name="l72" href="#l72">72</a><td> // http://connect.microsoft.com/IE/feedback/details/801823/setimmediate-and-messagechannel-are-broken-in-ie10<tr><td><a name="l73" href="#l73">73</a><td> if (goog.isFunction(goog.global.setImmediate) && (!goog.global.Window ||<tr><td><a name="l74" href="#l74">74</a><td> goog.global.Window.prototype.setImmediate != goog.global.setImmediate)) {<tr><td><a name="l75" href="#l75">75</a><td> goog.global.setImmediate(cb);<tr><td><a name="l76" href="#l76">76</a><td> return;<tr><td><a name="l77" href="#l77">77</a><td> }<tr><td><a name="l78" href="#l78">78</a><td> // Look for and cache the custom fallback version of setImmediate.<tr><td><a name="l79" href="#l79">79</a><td> if (!goog.async.nextTick.setImmediate_) {<tr><td><a name="l80" href="#l80">80</a><td> goog.async.nextTick.setImmediate_ =<tr><td><a name="l81" href="#l81">81</a><td> goog.async.nextTick.getSetImmediateEmulator_();<tr><td><a name="l82" href="#l82">82</a><td> }<tr><td><a name="l83" href="#l83">83</a><td> goog.async.nextTick.setImmediate_(cb);<tr><td><a name="l84" href="#l84">84</a><td>};<tr><td><a name="l85" href="#l85">85</a><td><tr><td><a name="l86" href="#l86">86</a><td><tr><td><a name="l87" href="#l87">87</a><td>/**<tr><td><a name="l88" href="#l88">88</a><td> * Cache for the setImmediate implementation.<tr><td><a name="l89" href="#l89">89</a><td> * @type {function(function())}<tr><td><a name="l90" href="#l90">90</a><td> * @private<tr><td><a name="l91" href="#l91">91</a><td> */<tr><td><a name="l92" href="#l92">92</a><td>goog.async.nextTick.setImmediate_;<tr><td><a name="l93" href="#l93">93</a><td><tr><td><a name="l94" href="#l94">94</a><td><tr><td><a name="l95" href="#l95">95</a><td>/**<tr><td><a name="l96" href="#l96">96</a><td> * Determines the best possible implementation to run a function as soon as<tr><td><a name="l97" href="#l97">97</a><td> * the JS event loop is idle.<tr><td><a name="l98" href="#l98">98</a><td> * @return {function(function())} The "setImmediate" implementation.<tr><td><a name="l99" href="#l99">99</a><td> * @private<tr><td><a name="l100" href="#l100">100</a><td> */<tr><td><a name="l101" href="#l101">101</a><td>goog.async.nextTick.getSetImmediateEmulator_ = function() {<tr><td><a name="l102" href="#l102">102</a><td> // Create a private message channel and use it to postMessage empty messages<tr><td><a name="l103" href="#l103">103</a><td> // to ourselves.<tr><td><a name="l104" href="#l104">104</a><td> var Channel = goog.global['MessageChannel'];<tr><td><a name="l105" href="#l105">105</a><td> // If MessageChannel is not available and we are in a browser, implement<tr><td><a name="l106" href="#l106">106</a><td> // an iframe based polyfill in browsers that have postMessage and<tr><td><a name="l107" href="#l107">107</a><td> // document.addEventListener. The latter excludes IE8 because it has a<tr><td><a name="l108" href="#l108">108</a><td> // synchronous postMessage implementation.<tr><td><a name="l109" href="#l109">109</a><td> if (typeof Channel === 'undefined' && typeof window !== 'undefined' &&<tr><td><a name="l110" href="#l110">110</a><td> window.postMessage && window.addEventListener) {<tr><td><a name="l111" href="#l111">111</a><td> /** @constructor */<tr><td><a name="l112" href="#l112">112</a><td> Channel = function() {<tr><td><a name="l113" href="#l113">113</a><td> // Make an empty, invisible iframe.<tr><td><a name="l114" href="#l114">114</a><td> var iframe = document.createElement('iframe');<tr><td><a name="l115" href="#l115">115</a><td> iframe.style.display = 'none';<tr><td><a name="l116" href="#l116">116</a><td> iframe.src = '';<tr><td><a name="l117" href="#l117">117</a><td> document.documentElement.appendChild(iframe);<tr><td><a name="l118" href="#l118">118</a><td> var win = iframe.contentWindow;<tr><td><a name="l119" href="#l119">119</a><td> var doc = win.document;<tr><td><a name="l120" href="#l120">120</a><td> doc.open();<tr><td><a name="l121" href="#l121">121</a><td> doc.write('');<tr><td><a name="l122" href="#l122">122</a><td> doc.close();<tr><td><a name="l123" href="#l123">123</a><td> // Do not post anything sensitive over this channel, as the workaround for<tr><td><a name="l124" href="#l124">124</a><td> // pages with file: origin could allow that information to be modified or<tr><td><a name="l125" href="#l125">125</a><td> // intercepted.<tr><td><a name="l126" href="#l126">126</a><td> var message = 'callImmediate' + Math.random();<tr><td><a name="l127" href="#l127">127</a><td> // The same origin policy rejects attempts to postMessage from file: urls<tr><td><a name="l128" href="#l128">128</a><td> // unless the origin is '*'.<tr><td><a name="l129" href="#l129">129</a><td> // TODO(b/16335441): Use '*' origin for data: and other similar protocols.<tr><td><a name="l130" href="#l130">130</a><td> var origin = win.location.protocol == 'file:' ?<tr><td><a name="l131" href="#l131">131</a><td> '*' : win.location.protocol + '//' + win.location.host;<tr><td><a name="l132" href="#l132">132</a><td> var onmessage = goog.bind(function(e) {<tr><td><a name="l133" href="#l133">133</a><td> // Validate origin and message to make sure that this message was<tr><td><a name="l134" href="#l134">134</a><td> // intended for us.<tr><td><a name="l135" href="#l135">135</a><td> if (e.origin != origin && e.data != message) {<tr><td><a name="l136" href="#l136">136</a><td> return;<tr><td><a name="l137" href="#l137">137</a><td> }<tr><td><a name="l138" href="#l138">138</a><td> this['port1'].onmessage();<tr><td><a name="l139" href="#l139">139</a><td> }, this);<tr><td><a name="l140" href="#l140">140</a><td> win.addEventListener('message', onmessage, false);<tr><td><a name="l141" href="#l141">141</a><td> this['port1'] = {};<tr><td><a name="l142" href="#l142">142</a><td> this['port2'] = {<tr><td><a name="l143" href="#l143">143</a><td> postMessage: function() {<tr><td><a name="l144" href="#l144">144</a><td> win.postMessage(message, origin);<tr><td><a name="l145" href="#l145">145</a><td> }<tr><td><a name="l146" href="#l146">146</a><td> };<tr><td><a name="l147" href="#l147">147</a><td> };<tr><td><a name="l148" href="#l148">148</a><td> }<tr><td><a name="l149" href="#l149">149</a><td> if (typeof Channel !== 'undefined' &&<tr><td><a name="l150" href="#l150">150</a><td> // Exclude all of IE due to<tr><td><a name="l151" href="#l151">151</a><td> // http://codeforhire.com/2013/09/21/setimmediate-and-messagechannel-broken-on-internet-explorer-10/<tr><td><a name="l152" href="#l152">152</a><td> // which allows starving postMessage with a busy setTimeout loop.<tr><td><a name="l153" href="#l153">153</a><td> // This currently affects IE10 and IE11 which would otherwise be able<tr><td><a name="l154" href="#l154">154</a><td> // to use the postMessage based fallbacks.<tr><td><a name="l155" href="#l155">155</a><td> !goog.labs.userAgent.browser.isIE()) {<tr><td><a name="l156" href="#l156">156</a><td> var channel = new Channel();<tr><td><a name="l157" href="#l157">157</a><td> // Use a fifo linked list to call callbacks in the right order.<tr><td><a name="l158" href="#l158">158</a><td> var head = {};<tr><td><a name="l159" href="#l159">159</a><td> var tail = head;<tr><td><a name="l160" href="#l160">160</a><td> channel['port1'].onmessage = function() {<tr><td><a name="l161" href="#l161">161</a><td> head = head.next;<tr><td><a name="l162" href="#l162">162</a><td> var cb = head.cb;<tr><td><a name="l163" href="#l163">163</a><td> head.cb = null;<tr><td><a name="l164" href="#l164">164</a><td> cb();<tr><td><a name="l165" href="#l165">165</a><td> };<tr><td><a name="l166" href="#l166">166</a><td> return function(cb) {<tr><td><a name="l167" href="#l167">167</a><td> tail.next = {<tr><td><a name="l168" href="#l168">168</a><td> cb: cb<tr><td><a name="l169" href="#l169">169</a><td> };<tr><td><a name="l170" href="#l170">170</a><td> tail = tail.next;<tr><td><a name="l171" href="#l171">171</a><td> channel['port2'].postMessage(0);<tr><td><a name="l172" href="#l172">172</a><td> };<tr><td><a name="l173" href="#l173">173</a><td> }<tr><td><a name="l174" href="#l174">174</a><td> // Implementation for IE6+: Script elements fire an asynchronous<tr><td><a name="l175" href="#l175">175</a><td> // onreadystatechange event when inserted into the DOM.<tr><td><a name="l176" href="#l176">176</a><td> if (typeof document !== 'undefined' && 'onreadystatechange' in<tr><td><a name="l177" href="#l177">177</a><td> document.createElement('script')) {<tr><td><a name="l178" href="#l178">178</a><td> return function(cb) {<tr><td><a name="l179" href="#l179">179</a><td> var script = document.createElement('script');<tr><td><a name="l180" href="#l180">180</a><td> script.onreadystatechange = function() {<tr><td><a name="l181" href="#l181">181</a><td> // Clean up and call the callback.<tr><td><a name="l182" href="#l182">182</a><td> script.onreadystatechange = null;<tr><td><a name="l183" href="#l183">183</a><td> script.parentNode.removeChild(script);<tr><td><a name="l184" href="#l184">184</a><td> script = null;<tr><td><a name="l185" href="#l185">185</a><td> cb();<tr><td><a name="l186" href="#l186">186</a><td> cb = null;<tr><td><a name="l187" href="#l187">187</a><td> };<tr><td><a name="l188" href="#l188">188</a><td> document.documentElement.appendChild(script);<tr><td><a name="l189" href="#l189">189</a><td> };<tr><td><a name="l190" href="#l190">190</a><td> }<tr><td><a name="l191" href="#l191">191</a><td> // Fall back to setTimeout with 0. In browsers this creates a delay of 5ms<tr><td><a name="l192" href="#l192">192</a><td> // or more.<tr><td><a name="l193" href="#l193">193</a><td> return function(cb) {<tr><td><a name="l194" href="#l194">194</a><td> goog.global.setTimeout(cb, 0);<tr><td><a name="l195" href="#l195">195</a><td> };<tr><td><a name="l196" href="#l196">196</a><td>};<tr><td><a name="l197" href="#l197">197</a><td><tr><td><a name="l198" href="#l198">198</a><td><tr><td><a name="l199" href="#l199">199</a><td>/**<tr><td><a name="l200" href="#l200">200</a><td> * Helper function that is overrided to protect callbacks with entry point<tr><td><a name="l201" href="#l201">201</a><td> * monitor if the application monitors entry points.<tr><td><a name="l202" href="#l202">202</a><td> * @param {function()} callback Callback function to fire as soon as possible.<tr><td><a name="l203" href="#l203">203</a><td> * @return {function()} The wrapped callback.<tr><td><a name="l204" href="#l204">204</a><td> * @private<tr><td><a name="l205" href="#l205">205</a><td> */<tr><td><a name="l206" href="#l206">206</a><td>goog.async.nextTick.wrapCallback_ = goog.functions.identity;<tr><td><a name="l207" href="#l207">207</a><td><tr><td><a name="l208" href="#l208">208</a><td><tr><td><a name="l209" href="#l209">209</a><td>// Register the callback function as an entry point, so that it can be<tr><td><a name="l210" href="#l210">210</a><td>// monitored for exception handling, etc. This has to be done in this file<tr><td><a name="l211" href="#l211">211</a><td>// since it requires special code to handle all browsers.<tr><td><a name="l212" href="#l212">212</a><td>goog.debug.entryPointRegistry.register(<tr><td><a name="l213" href="#l213">213</a><td> /**<tr><td><a name="l214" href="#l214">214</a><td> * @param {function(!Function): !Function} transformer The transforming<tr><td><a name="l215" href="#l215">215</a><td> * function.<tr><td><a name="l216" href="#l216">216</a><td> */<tr><td><a name="l217" href="#l217">217</a><td> function(transformer) {<tr><td><a name="l218" href="#l218">218</a><td> goog.async.nextTick.wrapCallback_ = transformer;<tr><td><a name="l219" href="#l219">219</a><td> });</table></pre></main><nav id="topnav"><div><div id="menubutton"><label for="sidenav-toggle">Menu</label></div><form id="searchbox"><div><input type="search" placeholder="Search" tabindex="1"></div></form></div></nav><nav id="sidenav"><input type="checkbox" id="sidenav-types-ctrl" /><input type="checkbox" id="sidenav-files-ctrl" /><input type="checkbox" id="sidenav-modules-ctrl" /><a id="sidenav-overview"><div><h4>Overview</h4></div></a><div id="sidenav-types"><label for="sidenav-types-ctrl"><h4>Types</h4></label><i>Loading</i></div><div id="sidenav-modules"><label for="sidenav-modules-ctrl"><h4>Modules</h4></label><i>Loading</i></div><div id="sidenav-files"><label for="sidenav-files-ctrl"><h4>Files</h4></label><i>Loading</i></div><a href="license.html"><div><h4>License</h4></div></a></nav><div id="push-footer"></div></div><footer><a href="https://github.com/jleyba/js-dossier">Generated by dossier</a></footer><script src="../../../../types.js"></script><script src="../../../../dossier.js"></script>