Functions inside functions

This is a very important concept to understand for fully understanding closures. Take a look at the example code below. It has a method called scopeCheck() inside which there is another function called innerScopeCheck(). Outside the function, there is a variable called globalScope, another variable that gets the return value of the scopeCheck() method and a couple of console.log() statements.

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const scopeCheck = () => {

    let localScope = "LOCAL";

    const innerScopeCheck = () => {

        let innerLocalScope = "INNER LOCAL";

        return globalScope + " { " + localScope + " { " + innerLocalScope + " }} ";

    }

    return innerScopeCheck;

}

let globalScope = "GLOBAL";

let thisIsAFunction = scopeCheck();

console.log(thisIsAFunction);

console.log(thisIsAFunction());