Remove first zero values from string using regex - regex

Question

I've created a string value using padStart method (padLeft), for example:
"5".padStart(19, "0")
which results into "0000000000000000005"
How can I get that 5 back using regex?
I've tested this:
/^0*(\d+)$/.exec(d)[1]
which return 5 correctly.
But this regex returns null for something like "00000012.22"
Samples:
5 > 5
005 > 5
0011.22 > 11.22 >> This is a first problem!
00100 >> 100
001001 >> 1001
00.5 >> 0.5 This is a second problem!
Working codes but without regex:
function toDb(d) {
if (d == null) return null;
var precisionIndex = d.indexOf('.');
return d.toString().padStart((29 + precisionIndex + 1), '0');
}
function fromDb(d) {
if (d == null) return null;
d = d.replace(/^0+/, ''); // I'd like to use regex here
if (d.indexOf('.') == 0) // I'd like to use regex here
d = '0' + d; // I'd like to use regex here
return d;
}
fromDb(toDb('0.5')) returns 0.5 for me. But I'd like to use regex in my codes.

Answer 1

Use String#replace method to replace leading 0.
console.log(
"0000000000000000005".replace(/^0+(?=\d)/, '')
)
console.log(
"000000000000000000.5".replace(/^0+(?=\d)/, '')
)
In the regex start anchor(^) assert the beginning position of the string and 0+ matches combination one or more repetition of 0, altogether ^0+ matches 0s at the beginning.
UPDATE : To avoid removing 0 just before the . use positive look ahead assertion, (?=\d) match up to the 0 which follows a digit.