JS Global Access Local variables

1.

Use this.name (variable name) in a function to assign a value, and when the function is called as a normal function , it can be accessed directly outside the function, because this point here points to the window:

    function fn () {        var r = 2;        THIS.SS = 0;        This.sum=function (num1,num2) {       return (num1+num2) *r;};    }    fn ();    var B = new fn ();    Console.log (ss);                0    Console.log (window.sum);    6    console.log (sum);            6

when a function is called as a method function, the situation is different, when this point changes and points to itself:

    function fn () {        var r = 2;        THIS.SS = 0;        This.sum=function (num1,num2) {       return (num1+num2) *r;};    }        var B = new FN ();/*        Console.log (ss);                Error Error    Console.log (window.sum);    Error error    console.log (sum);            Error Error *        //can access    Console.log (B.SS) through the instance;                0    Console.log (b.sum);    6

2.

    var A;    function fn2 () {        var b = 0;        return b;    };    A = Fn2 ();    Console.log (a); 0

JS Global Access Local variables