javascript - Remove leading and trailing zeros from a string

Question

I have a few strings like so:

str1 = "00001011100000";  // 10111
str2 = "00011101000000";  // 11101
...

I would like to strip the leading AND closing zeros from every string using regex with ONE operation.

So far I used two different functions but I would like to combine them together:

str.replace(/^0+/,'').replace(/0+$/,'');

Answer 1

You can just combine both of your regex using an OR clause (|):

var r = '00001011100000'.replace(/^0+|0+$/g, "");
//=> "10111"

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update: Above regex solutions replaces 0 with an empty string. To prevent this problem use this regex:

var repl = str.replace(/^0+(d)|(d)0+$/gm, '$1$2');

RegEx Demo

RegEx Breakup:

• ^: Assert start
• 0+: Match one or more zeroes
• (d): Followed by a digit that is captured in capture group #1
• |: OR
• (d): Match a digit that is captured in capture group #2
• 0+: Followed by one or more zeroes
• $: Assert end

Replacement:

Here we are using two back-references of the tow capturing groups:

$1$2

That basically puts digit after leading zeroes and digit before trailing zeroes back in the replacement.