javascript - jquery源码简单， "this"关键字容易混淆

Question

我对 jquery 1.7.3 源代码中的“this”关键字感到非常困惑。下面显示一些片段:

jQuery.fn = jQuery.prototype = {
constructor: jQuery,
init: function( selector, context, rootjQuery ) {
    var match, elem, ret, doc;

    // Handle $(""), $(null), or $(undefined)
    if ( !selector ) {
        return this;   
    }

    // Handle $(DOMElement)
    if ( selector.nodeType ) {
        this.context = this[0] = selector;
        this.length = 1;
        return this;
    }

<小时/>

if ( !selector ) {

  return this;   //why not only one "return" here?
                 //And does "this" refer to jQuery object?
                 //OTOH, this question is about why it returns "this".
}

Answer 1

返回此允许可链接插件调用，

$(whatever).plugin1().plugin2() etc

如果您不在插件中返回此，您将无法链接它链接速度很快，链接很酷你希望在 jquery 代码中尽可能多地链接

回答您的评论:不，您这样做(内部插件定义):

if ($("#div1").get(0)) {
   //do whatever to $("#div1")
   }
return this;

返回此在插件定义的末尾在任何情况下都不需要返回它