1//capitalize only the first letter of the string. 
2function capitalizeFirstLetter(string) {
3    return string.charAt(0).toUpperCase() + string.slice(1);
4}
5//capitalize all words of a string. 
6function capitalizeWords(string) {
7    return string.replace(/(?:^|\s)\S/g, function(a) { return a.toUpperCase(); });
8};

1const lower = 'this is an entirely lowercase string';
2const upper = lower.charAt(0).toUpperCase() + lower.substring(1);

1const uppercaseWords = str => str.replace(/^(.)|\s+(.)/g, c => c.toUpperCase());
2
3// Example
4uppercaseWords('hello world');      // 'Hello World'

1const str = 'captain picard';
2
3function capitalize(str) {
4  return str.charAt(0).toUpperCase() + str.slice(1);
5}
6
7const caps = str.split(' ').map(capitalize).join(' ');
8caps; // 'Captain Picard'

1const toTitleCase = (phrase) => {
2  return phrase
3    .toLowerCase()
4    .split(' ')
5    .map(word => word.charAt(0).toUpperCase() + word.slice(1))
6    .join(' ');
7};
8
9let result = toTitleCase('maRy hAd a lIttLe LaMb');
10console.log(result);

1const titleCase = function(text) {
2  let newText = '';
3  text = text.toLowerCase();
4  text = text.charAt(0).toUpperCase() + text.slice(1);
5  for (let i = 0; i < text.length; i++) {
6    if (text[i] === ' ') {
7      newText += ' ' + text[i+1].toUpperCase();
8      i++;
9    } else {
10      newText += text[i];
11    }
12  }
13  return newText;
14}