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<!DOCTYPE html>  <html lang="en"> <head> <meta charset="utf-8"> <title>CanJS - key</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=" parent expanded"> <a class="page" href="can-core.html" title="The best, most hardened and generally useful libraries in CanJS."> Core </a> <ul> <li class=" "> <a class="module" href="can-component.html" title="Create a custom element that can be used to manage widgets or application logic."> can-component </a> </li> <li class=" "> <a class="module" href="can-compute.html" title="Create an observable value."> can-compute </a> </li> <li class=" "> <a class="module" href="can-connect.html" title="can-connect provides persisted data middleware. Use it to assemble powerful model layers for any JavaScript project."> can-connect </a> </li> <li class=" "> <a class="module" href="can-define.html" title="Exports the define method that defines observable properties and their behavior on a prototype object."> can-define </a> </li> <li class=" "> <a class="module" href="can-define/list/list.html" title="Create observable lists."> can-define/list/list </a> </li> <li class=" "> <a class="module" href="can-define/map/map.html" title="Create observable objects."> can-define/map/map </a> </li> <li class=" "> <a class="function" href="can-route.html" title="Manage browser history and client state by synchronizing the window.location.hash with a map."> can-route </a> </li> <li class=" "> <a class="module" href="can-route-pushstate.html" title="Changes can-route to use pushstate to change the window's pathname instead of the hash. var route = require("can-route-pushstate"); route("{page}", { page: "home" }); route.ready(); route.attr("page", "user"); location.pathname; // -> "/user""> can-route-pushstate </a> </li> <li class=" "> <a class="module" href="can-set.html" title="can-set is a utility for comparing sets that are represented by the parameters commonly passed to service requests."> can-set </a> </li> <li class=" parent expanded"> <a class="module" href="can-stache.html" title="Live binding Mustache and Handlebars-compatible templates."> can-stache </a> <ul> <li> <span>Pages</span> <ul> <li class=" "> <a class="page" href="can-stache.magicTagTypes.html" title=""> Magic Tag Types </a> </li> <li class=" "> <a class="page" href="can-stache.scopeAndContext.html" title=""> Scope and Context </a> </li> <li class=" "> <a class="page" href="can-stache.expressions.html" title="In addition to different magic tag types, stache supports different expression types. These can be used in various combinations to call helper methods or viewModel methods. The following is an example of all the expressions combined:"> Expressions </a> </li> <li class=" "> <a class="page" href="can-stache.Acquisition.html" title="There are number of ways to acquire templates such as: raw text, a module loader, or script tags in the markup."> Template Acquisition </a> </li> <li class=" "> <a class="page" href="can-stache.Helpers.html" title="Helpers are functions that can be registered and called from within templates. These functions are typically used to provide functionality that is more appropriate for the view than the viewModel."> Helpers </a> </li> <li class=" "> <a class="page" href="can-stache.Binding.html" title="Live binding refers to templates which update themselves when their state or data changes. can-stache templates are able to listen to observables (like map, list, and can-compute) changing and update the page to reflect those changes."> Live Binding </a> </li> </ul> </li> <li> <span>Methods</span> <ul> <li class=" "> <a class="function" href="can-stache.from.html" title="Return a template loaded from an element."> from </a> </li> <li class=" "> <a class="function" href="can-stache.registerConverter.html" title="Register a helper for bidirectional value conversion."> registerConverter </a> </li> <li class=" "> <a class="function" href="can-stache.registerHelper.html" title="Register a helper."> registerHelper </a> </li> <li class=" "> <a class="function" href="can-stache.registerPartial.html" title="Register a partial. Register a partial template that can be rendered with can-stache.tags.partial."> registerPartial </a> </li> <li class=" "> <a class="function" href="can-stache.registerSimpleHelper.html" title="Register a helper that gets passed values."> registerSimpleHelper </a> </li> <li class=" "> <a class="function" href="can-stache.safeString.html" title="Indicate that a string does not need to be escaped to be safely inserted into the page."> safeString </a> </li> </ul> </li> <li> <span>Tags</span> <ul> <li class=" "> <a class="function" href="can-stache.tags.escaped.html" title="Insert the value of the expression into the output of the template."> {{expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.unescaped.html" title="Insert the unescaped value of the expression into the output of the template."> {{{expression}}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.section.html" title="Renders a subsection one or more times depending on the type of expression or the expression's return value."> {{#expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.close.html" title=""> {{/expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.inverse.html" title="Like can-stache.tags.section, but renders the opposite subsection depending on the type of expression or the expression's return value."> {{^expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.partial.html" title="Render another template within the current template."> {{>key}} </a> </li> <li class=" "> <a class="function" href="can-stache.tags.comment.html" title="A comment that doesn't get inserted into the rendered result."> {{!expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.else.html" title=""> {{else}} </a> </li> </ul> </li> <li> <span>Expressions</span> <ul> <li class=" "> <a class="typedef" href="can-stache/expressions/bracket.html" title=""> Bracket Expression </a> </li> <li class=" "> <a class="typedef" href="can-stache/expressions/call.html" title=""> Call Expression </a> </li> <li class=" "> <a class="typedef" href="can-stache/expressions/hash.html" title=""> Hash Expression </a> </li> <li class=" "> <a class="typedef" href="can-stache/expressions/helper.html" title=""> Helper Expression </a> </li> <li class=" "> <a class="typedef" href="can-stache/expressions/key-lookup.html" title=""> KeyLookup Expression </a> </li> <li class=" "> <a class="typedef" href="can-stache/expressions/literal.html" title="Specify a JavaScript primitive type."> Literal Expression </a> </li> </ul> </li> <li> <span>Key Operators</span> <ul> <li class=" "> <a class="typedef" href="can-stache/keys/at.html" title="Return whatever value is at a key, regardless if it's a function or a compute."> @at </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/compute.html" title="Pass a compute instead of a value if an observable is found within calls."> ~compute </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/current.html" title="Lookup a value in only the current context."> ./current </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/parent.html" title="Start looking for values in the parent context."> ../parent </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/special.html" title="Event bindings and some helpers like can-stache.helpers.each provide special values that start with % to prevent potential collisions with other values."> %special </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/this.html" title="Write out or return the current context."> this </a> </li> <li class=" "> <a class="typedef" href="can-stache/keys/variable.html" title="Store a variable local to the template."> *variable </a> </li> <li class="current parent expanded"> <a class="typedef" href="can-stache.key.html" title="A named reference to a value in the scope or helper scope in a template."> key </a> </li> </ul> </li> <li> <span>Helpers</span> <ul> <li class=" "> <a class="function" href="can-stache.helpers.if.html" title="can-stache.helpers.if"> {{#if expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.unless.html" title=""> {{#unless expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.each.html" title=""> {{#each expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.with.html" title="Changes the context within a block."> {{#with expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.log.html" title=""> {{log}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.is.html" title="Render something if two values are equal."> {{#is expressions}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.switch.html" title=""> {{#switch expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.case.html" title=""> {{#case expression}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.default.html" title=""> {{#default}} </a> </li> <li class=" "> <a class="function" href="can-stache.helpers.joinBase.html" title=""> {{joinBase expressions}} </a> </li> </ul> </li> <li> <span>Types</span> <ul> <li class=" "> <a class="typedef" href="can-stache.getterSetter.html" title="The getterSetter argument passed to registerConverter."> getterSetter </a> </li> <li class=" "> <a class="typedef" href="can-stache.helper.html" title="A helper function passed to can-stache.registerHelper. Given the arguments, returns the content that should be shown in the DOM or a function that will be called on the DOM element the helper was called on."> helper </a> </li> <li class=" "> <a class="typedef" href="can-stache.helperOptions.html" title="The options argument passed to a helper function when called by a helper."> helperOptions </a> </li> <li class=" "> <a class="typedef" href="can-stache.renderer.html" title="A function returned by can-stache that renders a template into an html documentFragment."> renderer </a> </li> <li class=" "> <a class="typedef" href="can-stache.sectionRenderer.html" title="Renders a section. These functions are usually provided as .fn and .inverse on a stache helper's options."> sectionRenderer </a> </li> <li class=" "> <a class="typedef" href="can-stache.simpleHelper.html" title="A helper function passed to can-stache.registerSimpleHelper."> simpleHelper </a> </li> </ul> </li> </ul> </li> <li class=" "> <a class="module" href="can-stache/helpers/route.html" title="Adds stache helpers that use can-route."> can-stache/helpers/route </a> </li> <li class=" "> <a class="module" href="can-stache-bindings.html" title="Provides template event, one-way, and two-way bindings."> can-stache-bindings </a> </li> </ul> </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=" "> <a class="page" href="can-legacy.html" title="Former libraries that we still accept patches for, but are not under active development."> Legacy </a> </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-core.html">Core</a></li> / <li><a href="can-stache.html">can-stache</a></li> / <li><a href="can-stache.key.html">key</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>key</h1> <div>typedef</div> </div> <section class="description"> <p>A named reference to a value in the <a href="can-view-scope.html" title="Create a lookup node for keys.">scope</a> or <a href="can-view-scope.Options.html" title="">helper scope</a> in a template.</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-stache/tree/v3.0.8/docs/keys/key.md">source</a></li>   </ul> </section> <div class="signature"> <h2 class="signature-title"> <code>key</code> </h2> <p>Looks up a value in the <a href="can-view-scope.html" title="Create a lookup node for keys.">scope</a> or <a href="can-view-scope.Options.html" title="">helper scope</a>. This results in a <a href="can-stache/expressions/key-lookup.html" title="">KeyLookup Expression</a>. <a href="can-stache/expressions/key-lookup.html" title="">KeyLookup Expression</a> expressions can provide different values depending on what type of expression they are within. These rules are detailed in <a href="can-stache/expressions/key-lookup.html" title="">KeyLookup Expression</a>.</p> <pre><code>{{name}} {{#canVote(age)}} </code></pre> </div> <div class="signature"> <h2 class="signature-title"> <code>EXPRESSION.key</code> </h2> <p>Looks up <code>key</code> on the result of a subexpression <code>EXPRESSION</code>.</p> <pre><code>{{person.first.name}} {{#if tasks.completed().length}} ... {{/if}} </code></pre> </div> <div class="signature"> <h2 class="signature-title"> <code>a\\.single\\.key</code> </h2> <p>Looks up a value without reading intermediate properties.</p> <pre><code>{{meta\\.data}} </code></pre> <p>This is deprecated. If you do have properties with dots in them, use a <a href="can-stache/expressions/bracket.html" title="">Bracket Expression</a>:</p> <pre><code>{{["meta.data"]}} </code></pre> </div> <section class="body"> <h2>Use</h2> <p>A key references a value within the <a href="can-view-scope.html" title="Create a lookup node for keys.">scope</a> of a template being rendered. In the following example, the key is <code>name</code>:</p> <pre><code><h1>{{name}}</h1> </code></pre> <p>If this template is rendered with:</p> <pre><code>{ name: "Austin" } </code></pre> <p>The template writes out:</p> <pre><code><h1>Austin</h1> </code></pre> <p>A scope is a collection of multiple contexts. By default, a key walks up the scope to each context until it finds a value. For example, a template like:</p> <pre><code>{{first}} {{last}} {{#children}} {{first}} {{last}} {{/children}} </code></pre> <p>Rendered with:</p> <pre><code>{ first: "Barry", last: "Meyer", children: [ {first: "Kim", last: "Sully"}, {first: "Justin"}, ] } </code></pre> <p>Writes out:</p> <pre><code>Barry Meyer Kim Sully Justin Meyer </code></pre> <p>When <code>last</code> is looked up on the <code>{first: "Justin"}</code> object and not found, it will then try to read the parent context's <code>last</code> property. This is why "Justin Meyer" is written out.</p> </section> <script type="text/javascript"> var docObject = {"src":{"path":"node_modules/can-stache/docs/keys/key.md"},"description":"A named reference to a value in the [can-view-scope scope] or [can-view-scope.Options helper scope] in a template.\n\n","type":"typedef","title":"key","types":[{"type":"String"}],"name":"can-stache.key","parent":"can-stache/keys","signatures":[{"code":"key","description":"\n\nLooks up a value in the [can-view-scope scope] or\n[can-view-scope.Options helper scope]. This results in a\n[can-stache/expressions/key-lookup]. [can-stache/expressions/key-lookup]\nexpressions can provide different values depending on what type of expression they\nare within. These rules are detailed in [can-stache/expressions/key-lookup].\n\n```\n{{name}}\n{{#canVote(age)}}\n```\n","params":[]},{"code":"EXPRESSION.key","description":"\n\nLooks up `key` on the result of a subexpression `EXPRESSION`.\n\n```\n{{person.first.name}}\n{{#if tasks.completed().length}} ... {{/if}}\n```\n","params":[]},{"code":"a\\\\.single\\\\.key","description":"\n\nLooks up a value without reading intermediate properties.\n\n\n```\n{{meta\\\\.data}}\n```\n\nThis is deprecated. If you do have properties with dots in them, use a [can-stache/expressions/bracket Bracket Expression]:\n\n```\n{{[\"meta.data\"]}}\n```\n","params":[]}],"comment":" ","pathToRoot":".."}; </script> </article> <footer><p>CanJS is part of <a href="http://donejs.com" target="_blank">DoneJS</a>. 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