how to change uppercase to lowercase with regex javascript

Question

It could be any string, it should match only the UPPERCASE part and change to lowercase, for example:

"It's around August AND THEN I get an email"

become

"It's around August and then I get an email"

as you can see the word It's, August and I should be ignored

Answer 1

Use /\b[A-Z]{2,}\b/g to match all-caps words and then .replace() with a callback that lowercases matches.

var string = "It's around August AND THEN I get an email",
  regex = /\b[A-Z]{2,}\b/g;

var modified = string.replace(regex, function(match) {
  return match.toLowerCase();
});

console.log(modified);
// It's around August and then I get an email

Also, feel free to use a more complicated expression. This one will look for capitalized words with 1+ length with "I" as the exception (I also made one that looked at the first word of a sentence different, but that was more complicated and requires updated logic in the callback function since you still want the first letter capitalized):

\b(?!I\b)[A-Z]+\b