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The default value is defined on demand, when the property is read for the first time.</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-define/tree/v1.0.4/docs/value.md">source</a></li>   </ul> </section> <div class="signature"> <h2 class="signature-title"> <code>value()</code> </h2> <p>A function can be provided that returns the default value used for this property, like:</p> <pre><code class="language-js">prop: { value: function(){ return []; } } </code></pre> <p>If the default value should be an object of some type, it should be specified as the return value of a function (the above call signature) so that all instances of this map don't point to the same object. For example, if the property <code>value</code> above had not returned an empty array but instead just specified an array using the next call signature below, all instances of that map would point to the same array (because JavaScript passes objects by reference).</p> <div class="returns"> <h3 class="returns-title">Returns</h3> <p> <code>{*}</code>: <p>The default value. This will be passed through setter and type.</p> </p> </div> </div> <div class="signature"> <h2 class="signature-title"> <code>value</code> </h2> <p>Any value can be provided as the default value used for this property, like:</p> <pre><code>prop: { value: 'foo' } </code></pre> <div class="parameters"> <h3 class="parameters-title">Parameters</h3> <ol> <li><b>defaultVal</b> <code>{*}</code>: <p>The default value, which will be passed through setter and type.</p> </li> </ol> </div> </div> <section class="body"> <p>There is a third way to provide a default value, which is explained in the <a href="can-define.types.ValueConstructor.html" title="Provides a constructor function to be used to provide a default value for a property.">Value</a> docs page. <code>value</code> lowercased is for providing default values for a property type, while <code>Value</code> uppercased is for providing a constructor function, which will be invoked with <code>new</code> to create a default value for each instance of this map.</p> <pre><code class="language-js">// A default age of `0`: var Person = DefineMap.extend({ age: { value: 0 }, address: { value: function(){ return {city: "Chicago", state: "IL"}; }; } }); </code></pre> </section> <script type="text/javascript"> var docObject = {"src":{"path":"node_modules/can-define/docs/value.md"},"description":"\nReturns the default value for instances of the defined type. 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