phpjs/functions/strings/strstr.js

php.js offers community built php functions in javascript

function strstr(haystack, needle, bool) {
  // From: http://phpjs.org/functions
  // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Onno Marsman
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // *     example 1: strstr('Kevin van Zonneveld', 'van');
  // *     returns 1: 'van Zonneveld'
  // *     example 2: strstr('Kevin van Zonneveld', 'van', true);
  // *     returns 2: 'Kevin '
  // *     example 3: strstr('name@example.com', '@');
  // *     returns 3: '@example.com'
  // *     example 4: strstr('name@example.com', '@', true);
  // *     returns 4: 'name'
  var pos = 0;

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