jQuery中extend()实现原理

jQuery.extend使用的几种方式

1.jQuery.extend(源对象)

 jQuery源代码：

 if(length == i){
      target = this;
      --i;
 }

 示例1：

 var person = {
     sex      : 'male',
     showName : function(name){
             alert("Name: " + name);
     }
 };
 jQuery.extend(person); // 将person对象扩展到jQuery（$）对象上
 jQuery.showName("admin"); // Name: admin
 $.showName("admin"); // Name: amdin
 alert("Sex: " + $.sex); // Sex: male

2.jQuery.extend(目标对象,源对象)

 var person = {
     language : ['java', 'c++', 'sql'],
     showName : function(name){
         alert("Name: " + name);
     }
 };
 var student = {
     showNum : function(num){
         alert("Num: " + num);
     }
 };
 jQuery.extend(student, person); // 将person对象扩展到指定的student对象上
 student.showName("admin");
 alert(student.language);

3.jQuery.extend(boolean,源对象)

 var person = {
     language : ['java', 'c++', 'sql'],
     showName : function(name){
         alert("Name: " + name);
     }
 };
 jQuery.extend(true, person); // 将person对象扩展jQuery对象上
 alert($.language); // java, c++, sql
 $.language.push('PL/SQL'); // 修改扩展后的对象
 alert(person.language); // java, c++, sql
 person.language.pop();

从上面例子中可以看出对$.language的修改不会影响到person中的language属性。这就是深度复制

4.jQuery.extend(boolean,目标对象,源对象)

 var person = {
     showName : function(name){
         alert("Name: " + name);
     }
 };
 var student = {
     language : ["java", "c++", "javascript"],
     showNum : function(num){
         alert("Num: " + num);
     }
 };
 var target = jQuery.extend(person, student);
 alert(target.language);     // java, c++, javascript
 target.language.push("PL/SQL");
 alert(student.language);    // java, c++, javascript, PL/SQL
 student.language.pop();
 alert(target.language);     // java, c++, javascript
 var target2 = jQuery.extend(true, person, student);
 alert(target2.language);    // java, c++, javascript
 target2.language.push("PL/SQL");
 alert(student.language);    // java, c++, javascript
 student.language.pop();
 alert(target2.language);    // java, c++, javascript, PL/SQL

转载自http://www.jb51.net/article/61478.htm