编写一个数组去重的方法

var arr = [1, 2, 3, 3, 4, 4, 5, 5, 6, 1, 9, 3, 25, 4];
function deRepeat() {
  var newArr = [];
  var obj = {};
  var index = 0;
  var l = arr.length;
  for (var i = 0; i < l; i++) {
    if (obj[arr[i]] == undefined) {
      obj[arr[i]] = 1;
      newArr[index++] = arr[i];
    } else if (obj[arr[i]] == 1) continue;
  }
  return newArr;
}
var newArr2 = deRepeat(arr);
alert(newArr2); //输出1,2,3,4,5,6,9,25