Clousure in JS

This is a brief explanation for closure in js.

Closure is a function that returns a function.

Basic Usage:

var saveFn = function (val) {
    return function () {
        return val;
    };
};

var retriveFn = saveFn(100);

console.log(retrieveFn());
//100

An argument 100 has been passed to closure, saveFn.

The function retrieveFn can now return values returned by saveFn, but it cannot change the entered value(100).

We can use this as the following:

var adder = function (a) {
    return function (b) {
        return a + b;
    };
};

var hi = adder('Hi ');
console.log(hi('Jamie')); //Hi Jamie

var calcNum = adder(100);
console.log(calcNum(50)); //150

same base function adder, used differently! :)