blocks|key|1207340|text|this指向正在调用特定方法的页面上的元素！|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1207341|请参阅http://learn.jquery.com/javascript-101/this-keyword/|1207342|entityMap|0|LINK|mutability|MUTABLE|url|http://learn.jquery.com/javascript-101/this-keyword/^0|0|4|0|3|1G|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

<code>this</code> points to the element on the page that a specific method is being invoked on!

refer to <a href="http://learn.jquery.com/javascript-101/this-keyword/" rel="nofollow">http://learn.jquery.com/javascript-101/this-keyword/</a>

blocks|key|1207400|text|http://learn.jquery.com/javascript-101/this-keyword/|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1207401|在JavaScript中，就像在大多数面向对象的编程语言中一样，this是一个特殊的关键字，用于在方法中引用调用方法的对象。它的值是通过一系列简单的步骤确定的：|style|CODE|1207402|如果使用Function.call()或Function.apply()调用函数，则将this设置为传递给.call()/.apply()的第一个参数。如果传递给.call()/.apply()的第一个参数是null或undefined，this将引用全局对象(这是web浏览器中的window对象)。|unordered-list-item|1207403|如果被调用的函数是使用Function.bind()创建的，则this将是在创建该函数时传递给.bind()的第一个参数。|1207404|如果函数作为对象的方法被调用，this将引用该对象。|1207405|否则，该函数将作为独立函数被调用，而该函数不附加到任何对象，而this将引用全局对象。|1207406|1207407|1207408|entityMap|0|LINK|mutability|MUTABLE|url^0|0|1G|0|0|W|4|0|4|F|K|G|17|4|1H|7|1P|8|29|7|2H|8|2W|4|31|9|3B|4|3X|6|0|B|F|V|4|1B|7|0|F|4|0|V|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]]|C|$]]|$1|D|3|E|5|6|7|13|8|@$A|14|B|15|F|G]]|9|@]|C|$]]|$1|H|3|I|5|J|7|16|8|@$A|17|B|18|F|G]|$A|19|B|1A|F|G]|$A|1B|B|1C|F|G]|$A|1D|B|1E|F|G]|$A|1F|B|1G|F|G]|$A|1H|B|1I|F|G]|$A|1J|B|1K|F|G]|$A|1L|B|1M|F|G]|$A|1N|B|1O|F|G]|$A|1P|B|1Q|F|G]|$A|1R|B|1S|F|G]]|9|@]|C|$]]|$1|K|3|L|5|J|7|1T|8|@$A|1U|B|1V|F|G]|$A|1W|B|1X|F|G]|$A|1Y|B|1Z|F|G]]|9|@]|C|$]]|$1|M|3|N|5|J|7|20|8|@$A|21|B|22|F|G]]|9|@]|C|$]]|$1|O|3|P|5|J|7|23|8|@$A|24|B|25|F|G]]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|26|8|@]|9|@]|C|$]]|$1|R|3|-4|5|6|7|27|8|@]|9|@]|C|$]]|$1|S|3|-4|5|6|7|28|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|4]]]]

<a href="http://learn.jquery.com/javascript-101/this-keyword/" rel="nofollow">http://learn.jquery.com/javascript-101/this-keyword/</a>

In JavaScript, as in most object-oriented programming languages, <code>this</code> is a special keyword that is used in methods to refer to the object on which a method is being invoked. The value of this is determined using a simple series of steps:

<ul>
<li>If the function is invoked using <code>Function.call()</code> or <code>Function.apply()</code>, <code>this</code> will be set to the first argument passed to <code>.call()</code>/<code>.apply()</code>. If the first argument passed to <code>.call()</code>/<code>.apply()</code> is <code>null</code> or <code>undefined</code>, <code>this</code> will refer to the global object (which is the <code>window</code> object in web browsers).</li>
<li>If the function being invoked was created using <code>Function.bind()</code>, <code>this</code> will be the first argument that was passed to <code>.bind()</code> at the time the function was created.</li>
<li>If the function is being invoked as a method of an object, <code>this</code> will refer to that object.</li>
<li>Otherwise, the function is being invoked as a standalone function not attached to any object, and <code>this</code> will refer to the global object.</li>
</ul>

blocks|key|1207443|text|this的值取决于它在其中显示的函数是如何调用的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1207444|您可以将它赋值给另一个变量：|1207445|给它一个信息更丰富的名字或|ordered-list-item|1207446|(更常见的情况下)，使该值在一个访问第一个函数范围的不同函数中可用。|1207447|1207448|1207449|在这种情况下，传递给widget.element.one()的匿名函数使用调用Nullpoll时的this值。如果它尝试使用this关键字，它将得到一个不同的值(该值将取决于one函数如何调用匿名函数)|1207450|entityMap^0|0|4|0|0|0|0|0|0|A|K|13|8|1D|4|1Q|4|2F|3|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$]]|$1|K|3|L|5|J|7|X|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]|$1|N|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|10|8|@$9|11|A|12|B|C]|$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]]|R|$]]

The value of <code>this</code> is determined by how the function it appears in was called.

You assign it to a different variable either:

<ol>
<li>To give it a more informative name or</li>
<li>(more commonly) so that the value is available in a different function which has access to the scope of the first function</li>
</ol>

In this particular case, the anonymous function passed to <code>widget.element.one()</code> uses the value of <code>this</code> from the call to <code>Nullpoll</code>. If it tried to use the <code>this</code> keyword, it would get a different value (what that value was would depend on how the <code>one</code> function called the anonymous function)

blocks|key|1633912|text|当在您的作用域内使用内联回调时(例如示例中的事件处理程序)，回调中的this值通常与父作用域不相同。因此，如果您希望从这些回调中访问父作用域中的this值，那么将其保存到父作用域中的局部变量是一种常见的设计模式。然后，在回调中，您仍然可以从父作用域引用该值，即使this在回调中可能有不同的值。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1633913|另一个好处是，一些最小化器可以使用局部变量而不是this来生成更小的代码，因为可以通过最小化器将局部变量重命名为单个字符变量，但不能将this重命名。|1633914|类似的问题，这里有很多答案：What+is+the+value+of+var+me+=+this;|1633915|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/7436709/what-is-the-value-of-var-me-this^0|Y|4|20|4|3N|4|0|O|4|1V|4|0|E|Z|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|13|8|@]|D|@$9|14|A|15|1|16]]|E|$]]|$1|J|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|Q]]]]

When using inline callbacks within your scope (such as the event handlers in your example), the value of <code>this</code> within the callbacks is often not the same as the parent scope. So, if you want access to the value of <code>this</code> in the parent scope from within those callbacks, then it is a common design pattern to save it to a local variable in the parent scope. Then, within the callbacks, you can still refer to that value from the parent scope even though <code>this</code> may have a different value within the callback.

As a secondary benefit, some minimizers can make smaller code by using a local variable rather than <code>this</code> because a local variable can be renamed to a single character variable by the minimizer, but <code>this</code> cannot be renamed.

Similar question with a bunch of answers here: <a href="https://stackoverflow.com/questions/7436709/what-is-the-value-of-var-me-this">What is the value of var me = this;</a>

often in some jQuery code I see that <code>this</code> is assigned to the variable in jQuery and I do not understand the reason for this approach?

This is an example of a jQuery plugin constructor:



<pre><code> //constructor
 function Nullpoll(element, options){
 var widget = this;
 widget.config = $.extend({}, defaults, options);
 widget.element = element;

 widget.element.on( "click", function() {
 alert("Test")
 });

 widget.element.one("change", function(e){
 widget.element.find("button").removeProp("disabled");
 });

 this.init();
 }
</code></pre>

Why should "this" be assigned to variable in jQuery?

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。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

在某些jQuery代码中，我经常看到this被分配给jQuery中的变量，而我不理解这种方法的原因？--这是一个jQuery插件构造函数的示例：    //constructor    function Nullpoll(element, options){        var widget = this;     ...

问为什么要将“此”分配给jQuery中的变量？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问为什么要将“此”分配给jQuery中的变量？EN