JS中二维数组去重

  function unique(arr) {
    var ret = [];
    var hash = {};
    for (var i = 0; i < arr.length; i++) {
      var item = arr[i];
      var key = typeof(item) + item
      if (hash[key] !== 1) {
        ret.push(item);
        hash[key] = 1;
    };
  };
  return ret
};

c = [1,2,3,3,4,4]
a = unique(c)
alert(a)