can

<!DOCTYPE html>  <html lang="en"> <head> <meta charset="utf-8"> <title>CanJS - can-map-define</title> <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no"> <link rel="stylesheet" type="text/css" href="./static/bundles/bit-docs-site/static.css"> <link rel="shortcut icon" sizes="16x16 24x24 32x32 48x48 64x64" href="/docs/images/canjs_favicon.ico"> <link rel="apple-touch-icon" sizes="57x57" href="../docs/images/canjs_favicon_57x57.png"> <link rel="apple-touch-icon-precomposed" sizes="57x57" href="../docs/images/canjs_favicon_57x57.png"> <link rel="apple-touch-icon" sizes="72x72" href="../docs/images/canjs_favicon_72x72.png"> <link rel="apple-touch-icon" sizes="114x114" href="../docs/images/canjs_favicon_114x114.png"> <link rel="apple-touch-icon" sizes="120x120" href="../docs/images/canjs_favicon_128x128.png"> <link rel="apple-touch-icon" sizes="144x144" href="../docs/images/canjs_favicon_144x144.png"> <link rel="apple-touch-icon" sizes="152x152" href="../docs/images/canjs_favicon_152x152.png"> <meta content="yes" name="apple-mobile-web-app-capable"> <meta name="apple-mobile-web-app-status-bar-style" content="white-translucent"> <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','https://www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-2302003-11', 'auto'); ga('send', 'pageview'); </script> </head> <body> <input type="checkbox" id="nav-trigger" class="nav-trigger"/> <label for="nav-trigger">Menu</label> <div id="everything"> <div id="left" class="column"> <div class="top-left"> <div class="brand"> <div class="logo"> <a href="../index.html" alt="CanJS"></a> <div class="dropdown project-dropdown"> <a href="https://donejs.com/">DoneJS</a> <a href="http://stealjs.com/">StealJS</a> <a href="http://jquerypp.com/">jQuery ++</a> <a href="https://funcunit.com/">FuncUnit</a> <a href="http://documentjs.com/">DocumentJS</a> </div> </div> <div class="version"> <div class="version-number"> 3.0.0 </div> <div class="dropdown version-dropdown"> <a href="https://v2.canjs.com">2.3.27</a> </div> </div> </div> <div class="search-bar"> <p>   </p> </div> </div> <div class="bottom-left"> <div class="social-side-container"> <ul class="social-side"> <li> <a class="header-mobile github" href="https://github.com/canjs/canjs" target="_blank"><img class="social-icon-small" src="../docs/images/github.png">Github</a> </li> <li> <a class="header-mobile twitter" href="https://twitter.com/canjs" target="_blank"><img class="social-icon-small" src="../docs/images/twitter.png">Twitter</a> </li> </ul> <ul class="social-side"> <li> <a class="header-mobile" href="https://gitter.im/canjs/canjs" target="_blank">Chat</a> </li> <li> <a class="header-mobile" href="http://forums.donejs.com/c/canjs" target="_blank">Forum</a> </li> </ul> </div> <ul> <li class=" "> <a class="page" href="guides.html" title="Welcome to CanJS! These guides are here to help you develop and improve your relationship with CanJS. After all, picking a JavaScript framework is a commitment. We want CanJS to be the framework you marry. This page helps you know how advance through the different stages of this relationship:"> Guides </a> </li> <li class=" "> <a class="page" href="can-core.html" title="The best, most hardened and generally useful libraries in CanJS."> Core </a> </li> <li class=" "> <a class="page" href="can-ecosystem.html" title="Useful libraries that extend or add important features to the core collection."> Ecosystem </a> </li> <li class=" "> <a class="page" href="can-infrastructure.html" title="Utility libraries that power the core and ecosystem collection."> Infrastructure </a> </li> <li class=" parent expanded"> <a class="page" href="can-legacy.html" title="Former libraries that we still accept patches for, but are not under active development."> Legacy </a> <ul> <li class=" "> <a class="module" href="can-ejs.html" title="EJS provides live ERB-style client-side templates."> can-ejs </a> </li> <li class=" "> <a class="module" href="can-list.html" title=""> can-list </a> </li> <li class=" "> <a class="module" href="can-map.html" title="Create observable objects."> can-map </a> </li> <li class=" "> <a class="module" href="can-map-backup.html" title=""> can-map-backup </a> </li> <li class="current parent expanded"> <a class="module" href="can-map-define.html" title="Defines the type, initial value, get, set, remove, and serialize behavior for attributes of a Map."> can-map-define </a> <ul> <li class=" "> <a class="function" href="can-map-define.TypeConstructor.html" title="Provides a constructor function to be used to convert any value passed into attr into an appropriate value"> Type </a> </li> <li class=" "> <a class="function" href="can-map-define.ValueConstructor.html" title="Provides a constructor function to be used to provide a default value for a certain property of a Map. This constructor will be invoked with new each time a new instance of the map is created."> Value </a> </li> <li class=" "> <a class="function" href="can-map-define._type.html" title="Converts a value passed to attr into an appropriate value."> type </a> </li> <li class=" "> <a class="typedef" href="can-map-define.attrDefinition.html" title="Defines the type, initial value, and get, set, and remove behavior for an attribute of a Map."> attribute definition </a> </li> <li class=" "> <a class="function" href="can-map-define.get.html" title="Specify what happens when a certain property is read on a map. get functions work like a compute and automatically update themselves when a dependent observable value is changed."> get </a> </li> <li class=" "> <a class="function" href="can-map-define.remove.html" title="Called when an attribute is removed."> remove </a> </li> <li class=" "> <a class="function" href="can-map-define.serialize.html" title="Called when an attribute is removed."> serialize </a> </li> <li class=" "> <a class="function" href="can-map-define.set.html" title="Specify what happens when a value is set on a map attribute."> set </a> </li> <li class=" "> <a class="function" href="can-map-define.value.html" title="Returns the default value for instances of this Map. This is called before init."> value </a> </li> </ul> </li> <li class=" "> <a class="module" href="can-view-href.html" title="Sets an element's href attribute so that it's url will set the specified attribute values on can-route."> can-view-href </a> </li> </ul> </li> </ul> </div> </div> <div id="right" class="column"> <div class="top-right"> <div class="top-right-top"> <ul class="top-right-bitovi"> <li class="dropdown"> <a href="http://bitovi.com" class="bitovi icon-bits">Bitovi</a> <ul class="dropdown-menu"> <li><a href="http://bitovi.com">Bitovi.com</a></li> <li><a href="http://bitovi.com/blog/">Blog</a></li> <li><a href="http://bitovi.com/consulting/">Consulting</a></li> <li><a href="http://bitovi.com/training/">Training</a></li> <li><a href="http://bitovi.com/open-source/">Open Source</a></li> </ul> </li> </ul> <div class="brand"> <div class="logo"> <a href="../index.html" alt="CanJS"></a> </div> </div> <ul class="top-right-links"> <li> <a href="https://gitter.im/canjs/canjs">Chat</a> </li> <li> <a href="http://forums.donejs.com/c/canjs">Forum</a> </li> <li> <a class="github-button nav-social" href="https://github.com/canjs/canjs" data-count-href="/canjs/canjs/stargazers" data-count-api="/repos/canjs/canjs#stargazers_count">Star</a> </li> <li> <a href="https://twitter.com/canjs" class="twitter-follow-button nav-social" data-show-count="true" data-show-screen-name="false">Follow @canjs</a><script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script> </li> </ul> </div> <div class="breadcrumb"> <li><a href="../index.html">CanJS</a></li> / <li><a href="can-legacy.html">Legacy</a></li> / <li><a href="can-map-define.html">can-map-define</a></li> <li class="breadcrumb-dropdown">/ <a> On this page</a> <ul class="on-this-page"></ul> </li> <div class="nav-toggle" title="Back to top"></div> </div> </div> <div class="bottom-right"> <article> <section class="title"> <div class="page-type"> <h1>can-map-define</h1> <div>module</div> </div> <section class="description"> <p>Defines the <code>type</code>, initial <code>value</code>, <code>get</code>, <code>set</code>, <code>remove</code>, and <code>serialize</code> behavior for attributes of a <a href="can-map.html" title="Create observable objects.">Map</a>.</p> </section> </section> <section class="on-this-page-table"> </section> <section class="title-footer"> <ul class="title-social"> <li> <a class="npm-button" href="https://www.npmjs.com/package/can-map-define"> <img src="https://img.shields.io/badge/npm%20package-3.0.0-brightgreen.svg" alt="npm package badge" /> </a> </li> <li> <a class="github-button nav-social" href="https://github.com/canjs/can-map-define" data-count-href="/canjs/can-map-define/stargazers" data-count-api="/repos/canjs/can-map-define#stargazers_count">Star</a> </li> </ul> <ul class="title-links">  <li><a href="//github.com/canjs/can-map-define/tree/v3.0.0/docs/define.md">source</a></li>   </ul> </section> <div class="signature"> <h2 class="signature-title"> <code>plugin</code> </h2> <div class="options"> <h3 class="options-title">Options</h3> <ul> <li> <b>define</b> <code>{Object<String,can.Map.prototype.define.attrDefinition>}</code>: <p>A map of attribute names to <a href="can-map-define.attrDefinition.html" title="Defines the type, initial value, and get, set, and remove behavior for an attribute of a Map.">attribute definition</a> objects.</p> </li> </ul> </div> </div> <section class="body"> <h2>Use</h2> <p>The <a href="can-map-define.html" title="Defines the type, initial value, get, set, remove, and serialize behavior for attributes of a Map.">define</a> plugin allows you to completely control the behavior of attributes on a <a href="can-map.html" title="Create observable objects.">Map</a>. To use it, you specify an <code>define</code> object that is a mapping of properties to <a href="can-map-define.attrDefinition.html" title="Defines the type, initial value, and get, set, and remove behavior for an attribute of a Map.">attribute definitions</a>. The following example specifies a Paginate Map:</p> <pre><code>var Paginate = Map.extend({ define: { count: { type: "number", value: Infinity, // Keeps count above 0. set: function(newCount){ return newCount < 0 ? 0 : newCount; } }, offset: { type: "number", value: 0, // Keeps offset between 0 and count set: function(newOffset){ var count = this.attr("count"); return newOffset < 0 ? 0 : Math.min(newOffset, !isNaN( count - 1) ? count - 1 : Infinity); } }, limit: { type: "number", value: 5 }, page: { // Setting page changes the offset set: function(newVal){ this.attr('offset', (parseInt(newVal) - 1) * this.attr('limit')); }, // The page value is derived from offset and limit. get: function (newVal) { return Math.floor(this.attr('offset') / this.attr('limit')) + 1; } } } }); </code></pre> <h2>Default behaviors</h2> <p>The <a href="can-map-define.html" title="Defines the type, initial value, get, set, remove, and serialize behavior for attributes of a Map.">define</a> plugin not only allows you to define individual attribute behaviors on a <a href="can-map.html" title="Create observable objects.">Map</a>, but you can also define default behaviors that would apply to any unspecified attribute. This is particularly helpful for when you need a particular behavior to apply to every attribute on a <a href="can-map.html" title="Create observable objects.">Map</a> but won't be certain of what every attribute will be.</p> <p>The following example is a <a href="can-map.html" title="Create observable objects.">Map</a> that is tied to <a href="can-route.html" title="Manage browser history and client state by synchronizing the window.location.hash with a map.">route</a> where only specified attributes that are serialized will be updated in the location hash:</p> <pre><code>var State = Map.extend({ define: { foo: { serialize: true }, '*': { serialize: false } } }); var state = new State(); // tie State map to the route route.map(state); route.ready(); state.attr('foo', 'bar'); state.attr('bar', 'baz'); window.location.hash; // -> #!foo=bar </code></pre> <h2>Overview</h2> <p>This plugin is a replacement for the now deprecated [can-map-attributes attributes] and [can-map-setter setter] plugins. It intends to provide a single place to define the behavior of all the properties of a <a href="can-map.html" title="Create observable objects.">Map</a>.</p> <p>Here is the cliffnotes version of this plugin. To define...</p> <ul> <li>The default value for a property - use <a href="can-map-define.value.html" title="Returns the default value for instances of this Map. This is called before init.">value</a></li> <li>That default value as a constructor function - use <a href="can-map-define.ValueConstructor.html" title="Provides a constructor function to be used to provide a default value for a certain property of a Map. This constructor will be invoked with new each time a new instance of the map is created.">Value</a></li> <li>What value is returned when a property is read - use <a href="can-map-define.get.html" title="Specify what happens when a certain property is read on a map. get functions work like a compute and automatically update themselves when a dependent observable value is changed.">get</a></li> <li>Behavior when a property is set - use <a href="can-map-define.set.html" title="Specify what happens when a value is set on a map attribute.">set</a></li> <li>How a property is serialized when <a href="can-map.prototype.serialize.html" title="Serialize this object to something that can be passed to JSON.stringify.">serialize</a> is called on it - use <a href="can-map-define.serialize.html" title="Called when an attribute is removed.">serialize</a></li> <li>Behavior when a property is removed - use <a href="can-map-define.remove.html" title="Called when an attribute is removed.">remove</a></li> <li>A custom converter method or a pre-defined standard converter called whenever a property is set - use <a href="can-map-define._type.html" title="Converts a value passed to attr into an appropriate value.">type</a></li> <li>That custom converter method as a constructor function - use <a href="can-map-define.TypeConstructor.html" title="Provides a constructor function to be used to convert any value passed into attr into an appropriate value">Type</a></li> </ul> <h2>Demo</h2> <p>The following shows picking cars by make / model / year:</p> <div class='demo_wrapper' data-demo-src='can/map/define/doc/examples/make-model-year.html'></div> </section> <script type="text/javascript"> var docObject = {"src":{"path":"node_modules/can-map-define/docs/define.md"},"description":"\nDefines the\n`type`, initial `value`, `get`, `set`, `remove`, and `serialize` behavior for attributes\nof a [can-map Map].\n","name":"can-map-define","type":"module","title":"can-map-define","types":[{"type":"plugin","options":[{"name":"define","description":"A map of\nattribute names to [can-map-define.attrDefinition attribute definition]\nobjects.\n","types":[{"type":"Object","template":[{"types":[{"type":"String"}]},{"types":[{"type":"can.Map.prototype.define.attrDefinition"}]}]}]}]}],"parent":"can-legacy","package":{"_args":[[{"raw":"can-map-define@3.0.0","scope":null,"escapedName":"can-map-define","name":"can-map-define","rawSpec":"3.0.0","spec":"3.0.0","type":"version"},"/Users/kevin/dev/canjs"]],"_from":"can-map-define@3.0.0","_id":"can-map-define@3.0.0","_inCache":true,"_location":"/can-map-define","_nodeVersion":"6.7.0","_npmOperationalInternal":{"host":"packages-12-west.internal.npmjs.com","tmp":"tmp/can-map-define-3.0.0.tgz_1476489374108_0.9224457654636353"},"_npmUser":{"name":"daffl","email":"daff@neyeon.de"},"_npmVersion":"3.10.3","_phantomChildren":{},"_requested":{"raw":"can-map-define@3.0.0","scope":null,"escapedName":"can-map-define","name":"can-map-define","rawSpec":"3.0.0","spec":"3.0.0","type":"version"},"_requiredBy":["/"],"_resolved":"https://registry.npmjs.org/can-map-define/-/can-map-define-3.0.0.tgz","_shasum":"38e66ac05a350033711fd940a466cd9ab8b91289","_shrinkwrap":null,"_spec":"can-map-define@3.0.0","_where":"/Users/kevin/dev/canjs","author":{"name":"Bitovi","email":"contact@bitovi.com","url":"http://bitovi.com"},"bit-docs":{"dependencies":{"bit-docs-glob-finder":"^0.0.5","bit-docs-dev":"^0.0.3","bit-docs-js":"^0.0.3","bit-docs-generate-readme":"^0.0.8"},"glob":{"pattern":"**/*.{js,md}","ignore":["**/node_modules/*","node_modules/**/*","**/*{-,_,}{test,qunit}{s,}.js"]},"readme":{"apis":"./doc/apis.json"},"parent":"can-map-define"},"bugs":{"url":"https://github.com/canjs/can-map-define/issues"},"dependencies":{"can-compute":"^3.0.0","can-event":"^3.0.1","can-map":"^3.0.1","can-util":"^3.0.1","jquery":"~2.2.1"},"description":"Define rich attribute behavior","devDependencies":{"bit-docs":"0.0.7","can-component":"^3.0.0-pre.11","can-fixture":"^0.3.0","can-list":"^3.0.0-pre.1","can-model":"^2.3.11","can-route":"^3.0.0-pre.8","can-stache":"^3.0.0-pre.11","done-serve":"^0.2.0","donejs-cli":"^0.8.0","generator-donejs":"^0.9.0","jshint":"^2.9.1","steal":"^0.16.0","steal-qunit":"^0.1.1","steal-tools":"^0.16.0","testee":"^0.2.4"},"directories":{},"dist":{"shasum":"38e66ac05a350033711fd940a466cd9ab8b91289","tarball":"https://registry.npmjs.org/can-map-define/-/can-map-define-3.0.0.tgz"},"gitHead":"97ef69cf88a482c0005d7822af1ffe28d2701b1a","homepage":"https://canjs.com","keywords":["canjs"],"main":"dist/cjs/can-map-define","maintainers":[{"name":"daffl","email":"daff@neyeon.de"},{"name":"iherndon","email":"ivan.herndon@gmail.com"},{"name":"justinbmeyer","email":"justin@bitovi.com"},{"name":"matthewp","email":"matthew@matthewphillips.info"},{"name":"phillipskevin","email":"kphillips86@gmail.com"},{"name":"sinjhin","email":"john@ardea.io"}],"name":"can-map-define","optionalDependencies":{},"readme":"ERROR: No README data found!","repository":{"type":"git","url":"git://github.com/canjs/can-map-define.git"},"scripts":{"build":"node build.js","develop":"done-serve --static --develop --port 8080","document":"bit-docs","jshint":"jshint ./*.js --config","postversion":"git push --tags && git checkout master && git branch -D release && git push","preversion":"npm test && npm run build","release:major":"npm version major && npm publish","release:minor":"npm version minor && npm publish","release:patch":"npm version patch && npm publish","release:pre":"npm version prerelease && npm publish","test":"npm run jshint && npm run testee","testee":"testee test/test.html --browsers firefox","version":"git commit -am \"Update dist for release\" && git checkout -b release && git add -f dist/"},"system":{"main":"can-map-define","npmAlgorithm":"flat"},"version":"3.0.0"},"comment":" ","pathToRoot":".."}; </script> </article> <footer><p>CanJS is part of <a href="http://donejs.com" target="_blank">DoneJS</a>. Created and maintained by the core <a href="https://donejs.com/About.html#section=section_Team" target="_blank">DoneJS team</a> and <a href="http://bitovi.com" target="_blank">Bitovi</a>. <strong>Currently 3.0.0.</strong></p></footer> </div> </div> </div> <script> steal = { instantiated: { "bundles/bit-docs-site/static.css!$css" : null } }; </script> <script type='text/javascript' data-main="bit-docs-site/static" src="./static/node_modules/steal/steal.production.js"></script> <script async defer src="https://buttons.github.io/buttons.js"></script> </body> </html>