I need a JavaScript method to allows me to convert the first letter of every word in a string to a capital letter like this: mike tyson wayne to Mike Tyson Wayne. The method should also be able to convert the first word after an hyphen to capital letter like this: mike-tyson wayne to Mike Tyson Wayne. The method should also be able to convert uppercase words to capitalize words like this: MIKE-TYSON WAYNE to Mike Tyson Wayne.

I have tried this method using regular expression gotten from another thread:

text.replace(/(^\w{1})|(\s{1}\w{1})/g, match => match.toUpperCase())

• (^\w{1}): match first char of string
• |: or
• (\s{1}\w{1}): match one char that came after one space
• g: match all
• match => match.toUpperCase(): replace with can take function, so; replace match with upper case match

It worked for converting the first letter of a string to capital letter and also works for the first letter of a string after space.

I added this expression that was supposed to cater for first letter of a string after space to the expression. The expression is (?:- |\d\. ).*

Combined with the first expression, it became:

text.replace(/(^\w{1})|(\s{1}\w{1})|(?:- |\d\. ).*/g, match => match.toUpperCase());

The problem is that the method above doesn't work for the strings after the dash but still works for the strings after space.

I need a JavaScript method to allows me to convert the first letter of every word in a string to a capital letter like this: mike tyson wayne to Mike Tyson Wayne. The method should also be able to convert the first word after an hyphen to capital letter like this: mike-tyson wayne to Mike Tyson Wayne. The method should also be able to convert uppercase words to capitalize words like this: MIKE-TYSON WAYNE to Mike Tyson Wayne.

I have tried this method using regular expression gotten from another thread:

text.replace(/(^\w{1})|(\s{1}\w{1})/g, match => match.toUpperCase())

• (^\w{1}): match first char of string
• |: or
• (\s{1}\w{1}): match one char that came after one space
• g: match all
• match => match.toUpperCase(): replace with can take function, so; replace match with upper case match

It worked for converting the first letter of a string to capital letter and also works for the first letter of a string after space.

I added this expression that was supposed to cater for first letter of a string after space to the expression. The expression is (?:- |\d\. ).*

Combined with the first expression, it became:

text.replace(/(^\w{1})|(\s{1}\w{1})|(?:- |\d\. ).*/g, match => match.toUpperCase());

The problem is that the method above doesn't work for the strings after the dash but still works for the strings after space.

• javascript
• regex
• string
• replace
• lookbehind

• There is another approach based on word boundaries. – Peter Seliger Commented Aug 6, 2021 at 9:24

3 Answers 3

• \d is a digit, so your expression matches a - or a digit followed by . ...
• {1} means one occurrence, which is the default anyways...

Try something like this:

/(^\w)|([-\s]\w)/g

A regex like ... /(?<=\b)\w/g or /(?<=\b)\p{L}/gu ... which both use a positive lookbehind for word boundaries but the second variant making use of Unicode property escapes might be a more generic yet viable approach ...

console.log(
  "mike-tyson wayne"
    .replace((/(?<=\b)\w/g), match => match.toUpperCase())
);
console.log(
  "MIKE-TYSON WAYNE"
    .toLowerCase()
    .replace((/(?<=\b)\p{L}/gu), match => match.toUpperCase())
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

let text = "UNIVERSITY OF CALIFORNIA-SAN DIEGO";
let pattern = /\w*/g;
let result = text.replace(pattern, function(word){
    return word.charAt(0).toUpperCase() + word.substr(1).toLowerCase();
});

//result = University Of California-San Diego