Js context introduction

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Origin https://www.youtube.com/watch?v=fjJoX9F_F5g

This in window context

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This In Global Function

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What is this

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This in Object

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Three methods to change context

Method 1

  var obj = {
    foo : function(){
      console.log(this === window);
    }
  };
  //call
  obj.foo.call(window);

Method 2

  var obj = {
    foo : function(){
      console.log(this === window);
    }
  };
  //call
  obj.foo.apply(window);

Method 3

  var obj = {
    foo : function(){
      console.log(this === window);
    }
  };
  //call
  var windowFoo = obj.foo.bind(window);
  windowFoo();

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Bind to change Context

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Element context in event

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Get parent context by reference variable**

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Get parent context by methd bind