JavaScript method invocation pattern and function invocation pattern

This two-day reading of the JavaScript language of the essence of the 4th chapter on the function of several modes of thinking about half a day.

Here's the method call pattern followed by the function invocation pattern.

Method invocation Pattern:

When a function is saved as a property of an object, we call it a method. When a method is called, this is bound to the object. If the invocation expression contains an action that extracts a property (A.name or A[name]), then he is called as a method.

 1  var  myObject = { 2  value:1,  3  double : function  () {// double is a method of MyObject object  4  this . Value = this.value*2 5  }  6  };  7  myObject. double  (); // 2  

Function call Pattern:

When a function is not a property of an object, then he is called as a function:

Note at this point that when a function is called in this mode, this is bound to the global object.

1 varMyObject = {2Value:13 };4MyObject.Double=function () {5     varHelper =function() {//Helper is not a property of an object, so this is a pointer to a Global object window6          This. Value = This. value*2;7     }8 Helper ();9 } ;TenMyObject.Double();//the value of 1,value does not change

We can define a variable for the method double and assign the value to this, then the intrinsic function can access this by that variable. By convention, we name that variable:

1 varMyObject = {2Value:13 };4MyObject.Double=function () {5     varthat = This;//define the variable that, and assign it a value of this6     varHelper =function () {7That.value = that.value*2;8     }9 Helper ();Ten } OneMyObject.Double();//2, because of the indirect access to the This,value eventually changed

JavaScript method invocation pattern and function invocation pattern