phpjs/functions/strings/lcfirst.js

php.js offers community built php functions in javascript

function lcfirst(str) {
  //  discuss at: http://phpjs.org/functions/lcfirst/
  // 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);
}