javascript undefined check not working

Question

in javascript i am trying to check if a "key" has been defined on an array, and if it doesn't create it and assign a value 0 to it.

the following code is part of a large script and it is inside some loops that change the value of project, country and month

console.log(typeof total_searches[project][country][month]);
if(typeof total_searches[project][country][month] !== "number");
    total_searches[project][country][month] = 0;

but for some reason, when it goes over this 'if' for the second time (all the keys are defined by then) it evaluates as TRUE and assigns 0 to it.

The console.log shows "number" when doing a debug using chrome.

i also tried if(!(month in total_searches[project][country]))

but it still evaluates to TRUE and goes in

what am i doing wrong?

thanks

So in log, it is a number and in the if clause it isn't? — pimvdb
– pimvdb, Commented Aug 10, 2011 at 16:40

Martin Hennings · Accepted Answer · 2011-08-10 16:41:11Z

5

You got a nasty sneaky semicolon after the if.

if(typeof total_searches[project][country][month] !== "number"); // <-- here

answered Aug 10, 2011 at 16:41

Martin Hennings

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brian brinley · Accepted Answer · 2011-08-10 16:40:39Z

1

!== also does a type match as well. try just !=

answered Aug 10, 2011 at 16:40

brian brinley

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Veger · Accepted Answer · 2011-08-10 16:41:15Z

1

You have a semicolon after your if-statement, which is seen as the true-statement. So the next line is always executed as it is seen as 'just' another line of code.

answered Aug 10, 2011 at 16:41

Veger

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