The This in SetTimeout ()

1:

1Window.id= ' Windowid ';2 functionM () {3      This. id= ' Mid ';4      This. f1=function() {Console.log ( This. id);}; 5      This. f2=function(){6         var that=this; 7 setTimeout (that.f1,5000);8         };9 }  Ten varm=NewM (); OneM.f2 ();//' Windowid '

2:

 window.id= ' windowid ' ;  function   M () { ;  function  () {     Console.log (this  .id);};  function   () {settimeout (  this.f1,5000  Span style= "color: #000000;"        >  };}  var  m=new          M (); M.f2 ();  //  ' Windowid '  

3:

Window.id= ' Windowid ';functionM () { This. id= ' Mid ';  This. f1=function() {Console.log ( This. id);};  This. f2=function() { setTimeout ( function () {this.f1 ();},5000);  };} varm=NewM (); M.f2 (); //error:undefined is not a function

4:

1Window.id= ' Windowid ';2 functionM () {3      This. id= ' Mid ';4      This. f1=function() {Console.log ( This. id);}; 5      This. f2=function(){6         var that=this;7         setTimeout (function () {that.f1 ();},5000);8         };9 }  Ten varm=NewM (); OneM.f2 ();//' Mid '

The This in SetTimeout ()