I'm trying to replace the capital letters in an entire string with their lower case counter parts while adding hyphen after it (unless its the last letter). So that Sunny&Cloudy would be e sunny-&-cloudy

var name = 'Sunny&Cloudy';
name.replace(/([A-Z])(.*)/, '\L$1');

I've tried this this myself but it only reaches the first capital letter adds a hyphen and stops. Leaving me with -S

I'm trying to replace the capital letters in an entire string with their lower case counter parts while adding hyphen after it (unless its the last letter). So that Sunny&Cloudy would be e sunny-&-cloudy

var name = 'Sunny&Cloudy';
name.replace(/([A-Z])(.*)/, '\L$1');

I've tried this this myself but it only reaches the first capital letter adds a hyphen and stops. Leaving me with -S

• javascript
• regex
• string
• replace

• But & is not a capital letter. Why do you want a hypen after it? Why noy sunny-&c-loudy? – GOTO 0 Commented May 29, 2019 at 21:58
• Which part of your code adds the hyphen? – PM 77-1 Commented May 29, 2019 at 21:58
• name.toLowerCase().replace(/&/g, "-&-") – Juan Commented May 29, 2019 at 21:59
• Can you add other examples so we can understand what you need to do in other scenarios? – Shidersz Commented May 29, 2019 at 22:00
• Hello, can you further explain where do you want to add the hyphen? Would they appear at the end of each word? Will all words have a & in between them? Thanks ! – DiegoTArg Commented May 29, 2019 at 22:01

4 Answers 4

If you want to convert Sunny&Cloudy into sunny-&-cloudy, then the following code should work:

var name = 'Sunny&Cloudy';
name.replace(/[A-Z][a-z]*/g, str => '-' + str.toLowerCase() + '-')
  // Convert words to lower case and add hyphens around it (for stuff like "&")
  .replace('--', '-') // remove double hyphens
  .replace(/(^-)|(-$)/g, ''); // remove hyphens at the beginning and the end

Basically you just use a function as the second parameter of .replace. (Reference)

It's not only replacing capitalized letter with their lowercase counterpart though, so you might want to revise your question description.

One possible approach for what you need is to use the replacement function of String.replace()

var name = 'Sunny&Cloudy';

let res = name.replace(/[A-Z&]/g, m => m === "&" ? "-and-" : m.toLowerCase());

console.log(res);

.as-console {background-color:black !important; color:lime;}
.as-console-wrapper {max-height:100% !important; top:0;}

You can use word boundaries \b to split the string into tokens, map everything to lowercase (except the last letter) and join the result together with a - dash

function dashed(str, sep) {
  let words = str.split(sep);
  return words.map(word => {
    let left = word.slice(0, -1).toLowerCase();
    let lastLetter = word.slice(-1);
    return `${left}${lastLetter}`
  }).join('-')

}

console.log(
  dashed("Sunny&CloudY&Rainy", /\b/)
)

The following regex should do the trick:

const regex = /(.+?\b)+?/g;
const str = 'Sunny&Cloudy&rainy';
const subst = '$1-';
const result = str.replace(regex, subst);

//make string lowercase + remove last '-'
console.log('Substitution result: ', result.toLowerCase().substring(0, result.length - 1));

By the way regex101. can e in handy to perfect a regex. You can select the 'ECMAScript/JavaScript' regex option. I use that site whenever I need to create a regex.