make single character in a word uppercase javascript code example

Example 1: javascript separate words by capital letter

"thisIsATrickyOne".split(/(?=[A-Z])/);

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();
    });
}