javascript/jquery: quick way to retrieve numeric from length attributes

I have attributes which denotes "5 px", "8px" "6em" and possible some others which I currently cannot think of right now. I'm interested in only the numeric value (ie 5, 8 or 6.) I kn开发者_运维百科ow i can do some regex but I'm wondering is there a short, documented, cross browser and readable jquery / javascript function out there which already provides this?

regards, Jeroen.

PS not sure if the wording in the title is correct please advice for alternatives.

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Use parseInt function:

var str = '5px';
alert(parseInt(str, 10));   // 5

Note that second argument of 10 represents base 10 there.

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In case they ever come back as 08px, (leading zero), use the radix of 10. Otherwise parseint() thinks your number is in octal.

var value = parseInt(str, 10);

It is probably never going to happen being returned from jQuery as a CSS property value, but a good habit to get into.

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A combination of parseInt/parseFloat (see the other answers) is probably your best bet, but just for kicks (and if you want to make your code completely unreadable), you can always use a Regex with extra cheese:

+(str.match(/(-?\d+(?:\.\d+)?)/)||[,0])[1]

The + operator converts the result to a Number, ||[,0] provides a default array if there's no number in str. [,0] might not work in all browsers, but [0,0] will.

:)