How inner anonymous function have scope of outer function?

Question

In the script shown below

$(function(){
    var outerValue="OuterValue";
    $('#btnScope').click(function(){
        alert(outerValue);
    });
});

The outer function (ie $()) executes when the page loads. At this time click event will be bound to anonymous function (which alerts). This function uses value of outerValue which might have lost scope after completing the ready($()) function. How this is possible? How could I know the scope of variable?

How the interpreter define its scope?

developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Closures — user1636522
– user1636522, Commented Dec 5, 2013 at 13:07

Halcyon · Accepted Answer · 2013-12-05 13:06:49Z

3

The outer scope is not lost. The scoping as you describe it is fairly accurate.

A variable's scope is roughly where it's defined (where var is). Any inner scope can access anything in it's outer scope. Only functions have scope though; not if, for, while or switch.

answered Dec 5, 2013 at 13:06

Halcyon

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5 Comments

Subin Jacob Over a year ago

That means the variable should keep the value always. How then its garbage collected? If I didn't used the variable inside another function would it had lost the scope?

Halcyon Over a year ago

If the variable isn't used it will be garbage collected. If you remove the click handler outerValue could be cleaned up.

Subin Jacob Over a year ago

Is closures possible in a typed language?

Halcyon Over a year ago

The typing of a language has no effect on whether closures are possible. JavaScript is weakly typed but it might just as well be strongly typed.

Subin Jacob Over a year ago

Sorry, I meant compiled languages.

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