为什么把 $自己和 $身体放在一起? 自己和 $自己是一样的吗

我通过理解别人的代码来学习 jQuery:

jQuery.fn.myFunc = function(options, callback) {


//stuff


jQuery(this)[settings.event](function(e) {
var self = this,
$self = jQuery( this ),
$body = jQuery( "body" );
//etc.
}


//more stuff


}

我的理解是 $引用 jQuery 对象。那么为什么把 $和 $self和 $body放在一起呢？self和 $self是一样的吗？

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No, it certainly is not. It is just another variable name. The $() you're talking about is actually the jQuery core function. The $self is just a variable. You can even rename it to foo if you want, this doesn't change things. The $ (and _) are legal characters in a Javascript identifier.

Why this is done so is often just some code convention or to avoid clashes with reversed keywords. I often use it for $this as follows:

var $this = $(this);
小开

self and $self aren't the same. The former is the object pointed to by "this" and the latter a jQuery object whose "scope" is the object pointed to by "this". Similarly, $body isn't the body DOM element but the jQuery object whose scope is the body element.

小开
最佳答案

$self has little to do with $, which is an alias for jQuery in this case. Some people prefer to put a dollar sign together with the variable to make a distinction between regular vars and jQuery objects.

example:

var self = 'some string';
var $self = 'another string';

These are declared as two different variables. It's like putting underscore before private variables.

A somewhat popular pattern is:

var foo = 'some string';
var $foo = $('.foo');

That way, you know $foo is a cached jQuery object later on in the code.

小开

This is pure JavaScript.

There is nothing special about $. It is just a character that may be used in variable names.

var $ = 1;
var $$ = 2;
alert($ + $$);

jQuery just assigns it's core function to a variable called $. The code you have assigns this to a local variable called self and the results of calling jQuery with this as an argument to a global variable called $self.

It's ugly, dirty, confusing, but $, self and $self are all different variables that happen to have similar names.

小开

The dollarsign as a prefix in the var name is a usage from the concept of the hungarian notation.


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