Nodejs Utililty Methods String Camel Case

String.prototype.toCamelCase = function() {
  var str = this.toLowerCase();
  var modified = '';
  var mark = false;
  for (var i = 0; i < str.length; i++) {
    if (str[i] === '_') {
      mark = true;
      continue;
    if (mark) {
      if (modified.length > 0) {
        modified += str[i].toUpperCase();
      } else {
        modified = str[i];
      mark = false;
    } else {
      modified += str[i];
  return modified;
};

String.prototype.toCamelCase = function() {
  return this.replace(/[- ](\w)/g, function(match) {
    return match[1].toUpperCase();
  });

"use strict";
var toCamelCase = function (string) {
    if (string.substr(0, 2) !== string.substr(0, 2).toUpperCase()) {
        return string.substr(0, 1).toLowerCase() + string.substr(1);
    else {
        return string;
};
...

String.prototype.toCamelCase  = jCube.String.toCamelCase  = function () {
  return this.replace( /-\D|-\d/g, function(s){ return s.charAt(1).toUpperCase()}).replace( /\s\D|\s\d/g, function(s){ return s.charAt(1).toUpperCase()});

String.prototype.toLittleCamelCase = function () {
  var sourceStr = this.toString();
  var str = '';
  var strArr = sourceStr.split('-');
  strArr.forEach(function (el) {
    str = str + el.firstUppserCase();
  })
  str = str.firstLowerCase();
  return str;
...

String.prototype.to_camelCase = String.prototype.to_camelCase || function(){
    var split = this.split('_').filter(Boolean);
    var len = split.length;
    var camelCaseString = '';
    for (var i=0;i<len;i++) {
        if(i===0){
            camelCaseString = camelCaseString + split[i].toLowerCase();
        else{
...

String.prototype.unCamelCase = function(){
  return this
    .replace(/([a-z])([A-Z])/g, '$1 $2')
    .replace(/\b([A-Z]+)([A-Z])([a-z])/, '$1 $2$3')
    .replace(/^./, function(str){ return str.toUpperCase(); })

String.prototype.underscore_to_camel = function() {
  return this.replace(/_[a-z]/, function(m){ return m.substring(1).toUpperCase(); })
String.prototype.capitalize = function() {
  return this.replace(/^[a-z]/, function(m){ return m.toUpperCase(); })
String.prototype.repeat = function(num) {
  return new Array( num + 1 ).join( this );