[英]What is a jQuery Object?
JavaScript kind of redefines what an Array means because an array is an object with a .length
property and methods like .slice()
and .join()
. JavaScript类重新定义了Array的含义,因为数组是具有.length
属性的对象,以及.slice()
和.join()
。
jQuery defines a jQuery object as "Array like", because it has a length
property but it doesn't have certain array methods like join()
. jQuery将jQuery对象定义为“Array like”,因为它具有length
属性,但它没有某些数组方法,如join()
。
If I were to define the jQuery object as an object, and forget about mentioning anything to do with an array, how would I define it? 如果我将jQuery对象定义为对象,并且忘记提及与数组有关的任何内容,我将如何定义它? What properties does it have besides length? 除长度外还有哪些属性?
I guess all the methods are what you see in the documentation, far exceeding the number of methods that are in an array. 我猜所有的方法都是你在文档中看到的,远远超过了数组中的方法数量。
A jQuery object is array-like which means that it contains zero or more indexes (properties which names are positive integers starting with zero). jQuery对象是类似数组的,这意味着它包含零个或多个索引(名称是从零开始的正整数的属性)。 Besides those indexes, a jQuery object contains these properties: 除了这些索引之外,jQuery对象还包含以下属性:
length
context
selector
And also around 140 inherited methods (which are defined on the jQuery.prototype
object - you can do console.dir(jQuery.prototype)
to get a full list... ). 还有大约140个继承的方法(在jQuery.prototype
对象上定义 - 你可以做console.dir(jQuery.prototype)
来获得一个完整的列表......)。
Note that jQuery objects do not contain (or inherit) the Array methods (slice, substr, ...). 请注意,jQuery对象不包含(或继承)Array方法(slice,substr,...)。 If you want to execute those methods on your jQuery object, use call
/ apply
. 如果要在jQuery对象上执行这些方法,请使用call
/ apply
。
For example, if you have 3 TEXTAREA elements on the page and you do this: 例如,如果页面上有3个TEXTAREA元素,则执行此操作:
var j = $('textarea');
then this j
jQuery object will contain these properties: 那么这个j
jQuery对象将包含以下属性:
0
- reference to the first TEXTAREA element 0
- 对第一个TEXTAREA元素的引用 1
- reference to the second TEXTAREA element 1
- 引用第二个TEXTAREA元素 2
- reference to the third TEXTAREA element 2
- 对第三个TEXTAREA元素的引用 length
- which is 3
length
- 这是3
context
- reference to the document
object context
- 对document
对象的引用 selector
- which is 'textarea'
selector
- 这是'textarea'
the jQuery object is an object which has jQuery对象是一个具有的对象
The length and numeric properties allow the object to respond like an array. length和numeric属性允许对象像数组一样响应。 You can run it in a for
loop or use functions like map
or each
on it. 您可以在for
循环中运行它,也可以使用map
或其中的each
函数。
I would recommend using your browser's debugger or Firebug and inspect a jQuery object. 我建议使用浏览器的调试器或Firebug并检查jQuery对象。 That will teach you a lot about how it is structured. 这将教会你很多关于它的结构。
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