Learning notes - Closures - Moment For Technology

In the first article, I want to take notes about closures and tidy up my thoughts

What is a closure?

One thing to note is that you need to use the var statement to define variables inside a function, or declare a global variable if you don’t.

var a=1;
var F = function(){
    var b=2;
    var N = function(){
        var c=3;
    };
};

a
b
c
a
b

closure
a
b
a

var

var a=1;
var F = function(){
    var b=2;
    var N = function(){
        var c=3;
        return b;
    };
    return N;
};

>b
Uncaught ReferenceError: b is not defined
>var f=F();
>f();
2

var f;
var F = function(){
    var b=2;
    var N = function(){
        var c=3;
        return b;
    };
    f=N;
};

>f();
2