Transform all text in a string to uppercase

Use String.toUpperCase() to transform all text in a string to uppercase.

var text = 'This sentence has some MIXED CASE LeTTeRs in it.';

// returns "THIS SENTENCE HAS SOME MIXED CASE LETTERS IN IT."
var upper = text.toUpperCase();

Source

https://vanillajstoolkit.com/reference/strings/string-touppercase/