By definition, a JavaScript closure ensures that the variable is a combination of a function along with references to its surrounding state. To understand this a little more clearly, we will make use of the Inspect command in Google Chrome. The below code snippet is a slight modification of the previous one.

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const scopeCheck = () => {

    let b = 20;

    const innerScopeCheck = () => {

        let a = 10;

        let ret = a + b;

        b++;

        return ret;

    }

    return innerScopeCheck;

}

let fun1 = scopeCheck();

let fun2 = scopeCheck();

​

console.dir(fun1);