phpjs/functions/strings/lcfirst.js

php.js offers community built php functions in javascript

function lcfirst(str) {
  // From: http://phpjs.org/functions
  // +   original by: Brett Zamir (http://brett-zamir.me)
  // *     example 1: lcfirst('Kevin Van Zonneveld');
  // *     returns 1: 'kevin Van Zonneveld'
  str += '';
  var f = str.charAt(0).toLowerCase();
  return f + str.substr(1);
}