blocks|key|3296461|text|不确定jQuery使用的是什么，但有一个bind函数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3296462|var+regularFunc+=+function()+{
++++console.log(this);
};

var+boundFunc+=+regularFunc.bind(123);

regularFunc();+//+logs+whatever+'this'+is+at+time+it+is+called+(e.g.+'window')
boundFunc();+++//+logs+123+at+all+times+since+that+is+specified+to+be+'this'|code-block|syntax|javascript|3296463|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind^0|K|4|K|4|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Not sure what jQuery uses but there is a <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind" rel="nofollow"><code>bind</code></a> function:

<pre><code>var regularFunc = function() {
 console.log(this);
};

var boundFunc = regularFunc.bind(123);

regularFunc(); // logs whatever 'this' is at time it is called (e.g. 'window')
boundFunc(); // logs 123 at all times since that is specified to be 'this'
</code></pre>

blocks|key|4764595|text|这一切都结束了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4764596|在定义像this这样的变量时，Javascript使用闭包。|offset|length|style|CODE|4764597|所以你可以这样做：|4764598|var+myFuncs+=+{

+++func1:+function(){
+++++++++this.func2+=+function()+{+alert('hello');}
+++++++++return+this;
+++},
+++func2:+function(){alert('HI')}

}|code-block|syntax|javascript|4764599|所以，如果你这样做了：|4764600|myFuncs.func1().func2();+//+alerts+'hello'|4764601|鉴于：|4764602|myFuncs.func2();+//+alerts+'HI'|4764603|entityMap^0|0|4|4|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|12|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|13|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|14|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|15|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|16|8|@]|9|@]|A|$]]|$1|U|3|V|5|L|7|17|8|@]|9|@]|A|$M|N]]|$1|W|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|X|$]]

its all in closure.

Javascript uses closure when defining variable like <code>this</code>.

so you can do things like:

<pre><code>var myFuncs = {

 func1: function(){
 this.func2 = function() { alert('hello');}
 return this;
 },
 func2: function(){alert('HI')}

}
</code></pre>

so if you do:

<pre><code>myFuncs.func1().func2(); // alerts 'hello'
</code></pre>

whereas:

<pre><code>myFuncs.func2(); // alerts 'HI'
</code></pre>

blocks|key|3296524|text|Function有两种方法可供使用：call和apply。使用这两个参数，传递要用于this的对象作为第一个参数。使用call，额外的参数一个接一个地传递：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3296525|functionName.call(this,+arg1,+arg2);|code-block|syntax|javascript|3296526|使用apply传入一个参数数组：|3296527|functionName.apply(this,+[arg1,+arg1]);|3296528|或者，您可以传递一个实际的参数对象：|3296529|function+someFunction+()
{
++++functionName.apply(this,+this.arguments);
}|3296530|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/h2ak8h2y%2528VS.94%2529.aspx|1|http://msdn.microsoft.com/en-us/library/4zc42wh1%2528VS.94%2529.aspx^0|0|8|16|4|1N|4|I|4|0|N|5|1|0|0|2|5|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]|$9|1C|A|1D|1|1E]]|E|$]]|$1|F|3|G|5|H|7|1F|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1G|8|@$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|1J|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1K|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1L|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]|10|$5|V|W|X|E|$Y|11]]]]

A <code>Function</code> has two methods that you can use: <a href="http://msdn.microsoft.com/en-us/library/h2ak8h2y%28VS.94%29.aspx" rel="nofollow">call</a> and <a href="http://msdn.microsoft.com/en-us/library/4zc42wh1%28VS.94%29.aspx" rel="nofollow">apply</a>. With both of these, pass the object you want to use for <code>this</code> as the first argument. Using <code>call</code>, the additional arguments are passed one by one:

<pre><code>functionName.call(this, arg1, arg2);
</code></pre>

Using <code>apply</code>, pass in an array of arguments:

<pre><code>functionName.apply(this, [arg1, arg1]);
</code></pre>

Or, you can pass an actual arguments object:

<pre><code>function someFunction ()
{
 functionName.apply(this, this.arguments);
}
</code></pre>

blocks|key|1086044|text|您可以使用call或apply+JavaScript方法：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1086045|function+myFunction()+{
+++//+you+want+"this"+to+be+your+element
}

var+element+=+SOMEDOMELEMENT;

myFunction.call(element,+/*+add+other+comma-separated+arguments+here,+if+any+*/);

myFunction.apply(element,+/*+add+an+array+of+arguments+here,+if+any+*/);|code-block|syntax|javascript|1086046|当使用call和apply时，它会将函数中的上下文(this)更改为您想要的任何元素。|1086047|entityMap^0|5|4|A|5|0|0|Q|4|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

You can use the <code>call</code> or <code>apply</code> JavaScript methods:

<pre><code>function myFunction() {
 // you want "this" to be your element
}

var element = SOMEDOMELEMENT;

myFunction.call(element, /* add other comma-separated arguments here, if any */);

myFunction.apply(element, /* add an array of arguments here, if any */);
</code></pre>

When call and apply are used, it changes the context (<code>this</code>) inside your function to be whatever element you want it to be.

blocks|key|4764679|text|常规的旧javascript/html也可以做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4764680|<button+id='something'+onclick='alert(this.id);'>Click+me</button>|code-block|syntax|javascript|4764681|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Regular old javascript/html also does it.

<pre><code>&lt;button id='something' onclick='alert(this.id);'&gt;Click me&lt;/button&gt;
</code></pre>

When jQuery calls a function as an event handler for a raised event, jQuery is somehow able to define "this" in the context of a function that it calls. In the following example, jQuery define this as the dom element that was clicked on.

<pre><code>&lt;input id="someButton" type="button" value="click me!"/&gt;
&lt;script type="text/javascript"&gt;
 $("#someButton").click(EventHandler);
 function EventHandler() 
 {
 alert($(this).attr("id")); //This raises an alert message "someButton"
 }
&lt;/script&gt;
</code></pre>

How does jQuery do this? I would like replicate this behaviour for my own custom framework.

javascript: Defining "this" in the context of a function

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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当jQuery调用一个函数作为引发事件的事件处理程序时，jQuery能够以某种方式在它所调用的函数的上下文中定义"this“。在下面的示例中，jQuery将其定义为被单击的dom元素。<input id="someButton" type="button" value="click me!"/><script type...

问javascript:在函数上下文中定义"this“
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