javascript how to replace first letter in word code example

Example 1: javascript capitalize first letter of each word

function titleCase(str) {
   var splitStr = str.toLowerCase().split(' ');
   for (var i = 0; i < splitStr.length; i++) {
       // You do not need to check if i is larger than splitStr length, as your for does that for you
       // Assign it back to the array
       splitStr[i] = splitStr[i].charAt(0).toUpperCase() + splitStr[i].substring(1);     
   }
   // Directly return the joined string
   return splitStr.join(' '); 
}

document.write(titleCase("I'm a little tea pot"));

Example 2: uppercase in word javascript

function toTitleCase(str) {
    return str.replace(/\w\S*/g, function(txt){
        return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
    });
}