JavaScript中call与apply的用法及继承实现解析

代码执行上下文切换示例

/*
 * 矩形
 */
function Rectangle(len,width) {
  this.len = len;
  this.width = width;
 
}
/*
 * 乘以
 */
function multiply(a,b) {
  return a * b;
}
// 矩形实例
var rectangle = new Rectangle(15, 30);
//求矩形面积
var proportion = multiply.call(rectangle,rectangle.len, rectangle.width);
// 等价于call
//var proportion = multiply.apply(rectangle,[rectangle.len, rectangle.width]);
 
document.write("矩形的面积是："+proportion);
document.write("<br/>");
 
document.write("/***********************分割线********************************/<br/>");
 
// 实现继承
function Persion(name) {
  this.name = name;
  this.sayHello = function () {
    return "hello，"+this.name;
  }
}
 
function Student(name,sex,school) {
  Persion.call(this,name);
  this.sex = sex;
  this.school = school;
 
  this.mySex = function () {
    return this.sex;
  }
  this.mySchool = function () {
    return this.school;
  }
}
 
var stu = new Student('fengjx','男','广西机电职业技术学院')
 
document.write("stu sayHello："+stu.sayHello());
document.write("<br/>");
document.write("stu sex is："+stu.mySex());
document.write("<br/>");
document.write("stu school is ："+stu.mySchool());
document.write("<br/>");