Why does the Javascript replace() function not do anything? [closed]

Answer 1

I am not sure, but the function replace() creates a new variable. Try this :

var CSS_Left = '450px';
CSS_Left = CSS_Left.replace('px', '');
alert(CSS_Left);

Answer 2

Because .replace() return a new string. If you want to update the old string you should write: CSS_Left = CSS_Left.replace('px', '');

Answer 3

The output of the replace call needs to be reassigned to CSS_Left

Answer 4

In JavaScript, Strings are immutable.

All types except objects define immutable values. Specifically, strings are immutable (unlike in C for instance).

So, str.replace returns a new string. Try this instead:

CSS_Left = CSS_Left.replace('px', '');

Or if you don't want to overwrite the original string, just do it in the alert call

alert(CSS_Left.replace('px', ''));

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It's worth noting that .replace can also take a regexp. Though it's not necessary in your case, you could do something like this to achieve the same result

CSS_Left = CSS_left.replace(/px$/, '');