window.jQuery 和 window.$ 是什么意思？
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What does window.jQuery and window.$ mean?
提问by code511788465541441
Are they native properties of windowif so why is it called jQuery, surely jquery came after javascript
它们是本机属性，window如果是这样，为什么它被称为 jQuery，肯定 jquery 是在 javascript 之后出现的
Edit: I was looking through jquery.js and found these two lines which made me wonder about what they mean exactly. If wouldn't window.Jquery be null since JQuery is not a variable of window?
编辑：我正在浏览 jquery.js，发现这两行让我想知道它们到底是什么意思。如果因为 JQuery 不是窗口变量，window.Jquery 不会为空吗？
_jQuery = window.jQuery,
_$ = window.$,
采纳答案by David Ziemann
I will pull from an article I linked to in a comment above:
我将从上面评论中链接到的一篇文章中提取：
As discussed in the JavaScript Basics section, valid names in JavaScript can be pretty much anything, as long as they don't begin with a number and don't include a hyphen. So, the $ in the code above is just a shorter, more convenient name for the jQuery function; indeed, in the jQuery source code, you'll find this near the end:
正如 JavaScript 基础部分所讨论的，JavaScript 中的有效名称几乎可以是任何名称，只要它们不以数字开头且不包含连字符。因此，上面代码中的 $ 只是 jQuery 函数的一个更短、更方便的名称；实际上，在 jQuery 源代码中，您会在接近尾声时发现：
// Expose jQuery to the global object
window.jQuery = window.$ = jQuery;
When you call the $() function and pass a selector to it, you create a new jQuery object. Of course, in JavaScript, functions are objects too, so that means that $ (and jQuery, of course) has properties and methods, too. For example, you can refer to the $.support property for information on what the current browser environment supports, and you use the $.ajax method to make an AJAX request.
当您调用 $() 函数并将选择器传递给它时，您就创建了一个新的 jQuery 对象。当然，在 JavaScript 中，函数也是对象，所以这意味着 $（当然还有 jQuery）也有属性和方法。例如，您可以参考 $.support 属性以获取有关当前浏览器环境支持的信息，并使用 $.ajax 方法发出 AJAX 请求。
Basically, jQuery (when you include it) creates functions at window.$ and window.jquery. Then it sets $ equal to both of those to $ for convenience.
基本上，jQuery（当你包含它时）在 window.$ 和 window.jquery 创建函数。然后为方便起见，它将 $ 等于这两个设置为 $。
回答by BrunoLM
jQueryis a javascript library
jQuery是一个 javascript 库
jQuery is a fast, small, and feature-rich JavaScript library. It makes things like HTML document traversal and manipulation, event handling, animation, and Ajax much simpler with an easy-to-use API that works across a multitude of browsers. With a combination of versatility and extensibility, jQuery has changed the way that millions of people write JavaScript. http://jquery.com/
jQuery 是一个快速、小巧且功能丰富的 JavaScript 库。它通过易于使用的 API 使 HTML 文档遍历和操作、事件处理、动画和 Ajax 等工作变得更加简单，该 API 可在多种浏览器上运行。jQuery 结合了多功能性和可扩展性，改变了数百万人编写 JavaScript 的方式。 http://jquery.com/
Once you include the script on the page it will create the objects jQueryand $on the global context (window). It is not native.
一旦你包括页面上的脚本，它会创建对象jQuery，并$在全球范围内（窗口）。它不是原生的。
These
这些
_jQuery = window.jQuery,
_$ = window.$,
Are internal mappings in case of overwrite. You can use the function .noConflictto restore the previous value of window.$preventing conflicts with prototypeand other libraries
在覆盖的情况下是内部映射。您可以使用该功能.noConflict恢复以前window.$防止与prototype其他库发生冲突的值
回答by Quentin
windowis the default / global object. Any time you assign a value, and aren't explicit about the object to which it will be attached then it is going to be assigned to a property of the global object unless there is a local variable to assign it to first (see section 3.b. of PutValue);
window是默认/全局对象。任何时候您分配一个值，并且不明确说明它将附加到的对象时，它将被分配给全局对象的属性，除非有一个局部变量首先分配给它（参见第 3 节.b. PutValue);
Any global is going to be a property of it.
任何全局都将成为它的一个属性。
