How exactly works the Javascript variable scope?

Question

I am pretty new in JavaScript and I have some doubts related to the variable scope.

So I tryed to do this example:

function outer() {

    alert("INTO outer()");
    var val1 = 1;

    inner();

    alert(val2);
}

function inner() {
    alert("INTO inner()");

    val2 = 2;


}

outer();

In this simple example the outer() function is perform, in this function I call the inner() function that declare and initializes the val2 variable. Then come back to the outer() function and from here I access and print the val2 value.

So it seam to me that in Javascript I can access to the variable defined in the inner function from the outer function but I can't access to the variable declared in the outer function from the inner function.

Is it true? If it is true why this choose?

Sanjay Maharjan · Answer 1 · 2015-06-21T15:11:37.783

3

It is true..The use of var in function 'outer' makes val1 local variable whereas val2 of function 'inner' has global scope since the keyword var is not used.

edited Jun 21 '15 at 15:11

answered Jun 21 '15 at 14:57

Sanjay Maharjan

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score 2 · Accepted Answer · answered Jun 21 '15 at 14:52

2

The declaration in your "inner" function is missing the var keyword. That makes val2 a global symbol.

answered Jun 21 '15 at 14:52

Pointy

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How exactly works the Javascript variable scope?

2 Answers2