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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-list.html">can-list</a></li> / <li><a href="can-list.prototype.map.html">map</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>map</h1> <div>function</div> </div> <section class="description"> <p>Call a function on each element of a List and return a new List instance from the results.</p> </section> </section> <section class="on-this-page-table"> </section> <section class="title-footer"> <ul class="title-links">  <li><a href="//github.com/canjs/can-list/tree/v3.0.0/docs/prototype.map.md">source</a></li>   </ul> </section> <div class="signature"> <h2 class="signature-title"> <code>list.map( callback(item, index, listReference), context )</code> </h2> <div class="parameters"> <h3 class="parameters-title">Parameters</h3> <ol> <li><b>callback</b> <code>{function(*, Number, <a href="can.List.html" title="undefined">can.List</a>)}</code>: <p>A function to call with each element of the list.</p> </li> <li><b>context</b> <code>{Object}</code>: <p>An optional object to use as <code>this</code> inside the callback.</p> </li> </ol> </div> <div class="returns"> <h3 class="returns-title">Returns</h3> <p> <code>{<a href="can.List.html" title="undefined">can.List</a>}</code>: <p>A new can.List instance.</p> </p> </div> </div> <section class="body"> <pre><code>var list = new List([1, 10, 100, 1000, 10000, 100000]); var newList = list.map(function(element, index, listReference) { var result; switch(index) { case 0: { result = false; break; } case 1: { result = undefined; break; } case 2: { result = element; break; } case 3: { result = element * 5; break; } default: { result = listReference[index] /= 2; break; } } return result; }); console.log(list); // [ 1, 10, 100, 1000, 5000, 50000] console.log(newList); // [false, undefined, 100, 5000, 5000, 50000] </code></pre> </section> <script type="text/javascript"> var docObject = {"src":{"path":"node_modules/can-list/docs/prototype.map.md"},"description":"Call a function on each element of a List and return a new List instance from the results. 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