javascript make change case code example

Example 1: javascript lowercase string

var str = "My Big Boy!"
var res = str.toLowerCase(); //res is "my big boy!"

Example 2: string to title case javascript

function titleCase(sentence) {
  let sentence = string.toLowerCase().split(" ");
  for (let i = 0; i < sentence.length; i++) {
    sentence[i] = sentence[i][0].toUpperCase() + sentence[i].slice(1);
  }
  
  return sentence.join(" ");
}