phpjs/functions/strings/stristr.js

php.js offers community built php functions in javascript

function stristr(haystack, needle, bool) {
  //  discuss at: http://phpjs.org/functions/stristr/
  // original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // bugfixed by: Onno Marsman
  //   example 1: stristr('Kevin van Zonneveld', 'Van');
  //   returns 1: 'van Zonneveld'
  //   example 2: stristr('Kevin van Zonneveld', 'VAN', true);
  //   returns 2: 'Kevin '

  var pos = 0;

  haystack += '';
  pos = haystack.toLowerCase()
    .indexOf((needle + '')
      .toLowerCase());
  if (pos == -1) {
    return false;
  } else {
    if (bool) {
      return haystack.substr(0, pos);
    } else {
      return haystack.slice(pos);
    }
  }
}