CODEWITHSUNDEEP
javascriptfunctionscopepublic
user443946
user443946

Reputation: 845

Javascript function scope

Why does the alert print 2 in the below example? var a is unknown to function n...

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>

    <title>Test Doc</title>
    <script type="text/javascript">
        var a = 1;
        function f() {
            var a = 2;
            function n() {
                alert(a);
            }
            n();
        }
        f();
    </script>
</head>

<body>


</body>
</html>

Upvotes: 1

Views: 466

Answers (3)

Sai Kalyan Kumar Akshinthala
Sai Kalyan Kumar Akshinthala

Reputation: 11844

a is decalred as a global variable and given a value of 1. a is also declared inside the function f() and given a value of 2. Function n() is declared inside the function f() and called after the assignment to the "inner" a.

So when n is called, the identifier a will be resolved from the scope of n. The first variable object on the scope chain with an a property is the one declared in f, so its value is returned.

Upvotes: 0

alex
alex

Reputation: 490283

JavaScript functions inherit their parent's scope. Inner variables shadow parent scope variables with the same name.

Further Reading.

Upvotes: 5

Shrinath
Shrinath

Reputation: 8118

It would alert "2".

Test your javascript examples here : jsfiddle.net

Your example is pasted here : your javascript example

And why the heck is var a unknown to n() ??

Upvotes: 0

Related Questions