JS call()及apply()方法使用实例汇总

  //例1
  <script>
    window.color = 'red';
    document.color = 'yellow';

    var s1 = {color: 'blue' };
    function changeColor(){
      console.log(this.color);
    }

    changeColor.call();     //red (默认传递参数)
    changeColor.call(window);  //red
    changeColor.call(document); //yellow
    changeColor.call(this);   //red
    changeColor.call(s1);    //blue

  </script>

  //例2
  var Pet = {
    words : '...',
    speak : function (say) {
      console.log(say + ''+ this.words)
    }
  }
  Pet.speak('Speak'); // 结果：Speak...

  var Dog = {
    words:'Wang'
  }

  //将this的指向改变成了Dog
  Pet.speak.call(Dog, 'Speak'); //结果： SpeakWang

  //例1
  <script>
    window.number = 'one';
    document.number = 'two';

    var s1 = {number: 'three' };
    function changeColor(){
      console.log(this.number);
    }

    changeColor.apply();     //one (默认传参)
    changeColor.apply(window);  //one
    changeColor.apply(document); //two
    changeColor.apply(this);   //one
    changeColor.apply(s1);    //three

  </script>

  //例2
  function Pet(words){
    this.words = words;
    this.speak = function () {
      console.log( this.words)
    }
  }
  function Dog(words){
    //Pet.call(this, words); //结果： Wang
    Pet.apply(this, arguments); //结果： Wang
  }
  var dog = new Dog('Wang');
  dog.speak();

  function add(c,d){
    return this.a + this.b + c + d;
  }

  var s = {a:1, b:2};
  console.log(add.call(s,3,4)); // 1+2+3+4 = 10
  console.log(add.apply(s,[5,6])); // 1+2+5+6 = 14 

  <script>
    window.firstName = "Cynthia"; 
    window.lastName = "_xie";

    var myObject = {firstName:'my', lastName:'Object'};

    function getName(){
      console.log(this.firstName + this.lastName);
    }

    function getMessage(sex,age){
      console.log(this.firstName + this.lastName + " 性别: " + sex + " age: " + age );
    }

    getName.call(window); // Cynthia_xie
    getName.call(myObject); // myObject

    getName.apply(window); // Cynthia_xie
    getName.apply(myObject);// myObject

    getMessage.call(window,"女",21); //Cynthia_xie 性别: 女 age: 21
    getMessage.apply(window,["女",21]); // Cynthia_xie 性别: 女 age: 21

    getMessage.call(myObject,"未知",22); //myObject 性别: 未知 age: 22
    getMessage.apply(myObject,["未知",22]); // myObject 性别: 未知 age: 22

  </script>