javascript variable scoping

Question

Why does javascript allow the creation of global variables in local code?
An example

function f() { x=10; }
function g() { print(x); }
f(x);
g(x);

A design error. This flaw has been removed in ES5 strict mode. — Šime Vidas
– Šime Vidas, Commented Jul 12, 2011 at 13:34
Why not? I suppose it could make naming conflicts, but you should be giving better variable names if that is an issue. — josh.trow
– josh.trow, Commented Jul 12, 2011 at 13:35
Source for my statement above: es5.github.com/#C (fourth bullet) — Šime Vidas
– Šime Vidas, Commented Jul 12, 2011 at 13:40
And a live demo that demonstrates this: jsfiddle.net/simevidas/r3Hjp/1 (doesn't work in older browsers) — Šime Vidas
– Šime Vidas, Commented Jul 12, 2011 at 13:43
Thank you Šime, could you post these comments as an answer? — titus
– titus, Commented Jul 12, 2011 at 13:45

Radu · Accepted Answer · 2011-07-12 13:34:24Z

3

When you don't preface variables with var they are automatically in the global scope.

answered Jul 12, 2011 at 13:34

Radu

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Comments

Quentin · Accepted Answer · 2011-07-12 13:35:03Z

1

Why does javascript allow the creation of global variables in local code?

Because it isn't a perfect language.

Use the var keyword to limit the scope of variables.

answered Jul 12, 2011 at 13:35

Quentin

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jenovachild · Accepted Answer · 2011-07-12 13:35:45Z

0

I think you need to specify var before the variable declaration to make it in scope.

answered Jul 12, 2011 at 13:35

jenovachild

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