Camel case to lowercase first character regex

Question

I'm trying to rename a certain type of strings with .replace() and REGEX.

myCustomClass -> customClass
myCustomOption -> customOption

I need something that in effect does this string.charAt(0).toLowerCase() + string.slice(1), but with REGEX.

So I'm working on something like this

var myCustomClass = 'myCustomClass',
    myCustomOption = 'myCustomOption';
    
document.body.innerHTML = myCustomClass.replace('my','')
                         .replace(/([A-Z])/, ('$1').toLowerCase() ) + '<br>'

document.body.innerHTML += myCustomOption.replace('my','')
                          .replace(/([A-Z])/, ('$1').toLowerCase() )

The results are CustomClass and CustomOption, which is not what I was expecting. How can I do this please?

Use a function as second parameter to replace. All you are doing is `.replace(/[A_Z])/, '$1' /* result of toLowerCase call */)` which doesn't do anything. — ASDFGerte, Feb 02 '21 at 07:53
Thanks @ASDFGerte I posted an answer, hope it helps others, you're the man. — thednp, Feb 02 '21 at 08:04

thednp · Answer 1 · 2021-02-02T08:05:36.667

As suggested, this is the solution:

string.replace(/[A-Z]/, (match) => match.toLowerCase() )

Demo:

var myCustomClass = 'myCustomClass',
    myCustomOption = 'myCustomOption';
    
document.body.innerHTML = myCustomClass.replace('my','')
                         .replace(/[A-Z]/, (match) => match.toLowerCase() ) + '<br>'

document.body.innerHTML += myCustomOption.replace('my','')
                          .replace(/[A-Z]/, (match) => match.toLowerCase() )

Camel case to lowercase first character regex

1 Answers1