javascript - Check for duplicates in an array -

i have function check serialized form data if there duplicates values in it.

    s = $('#multiselectform').serialize();     var x = [];     var y = [];     x = s.split("&");     (var = x.length - 1; >= 0; i--) {         y.push(x[i].split("="));     };     var c = 0;     var e = 0;     (var = y.length - 1; >= 0; i--) {         if (y[i][1] == y[c][1]) {             e++;             $('.duplicatealert').show();         } else {             $('.duplicatealert').hide();         };         c++;     }; 

basically, split string produced serialize() function , push data arrays.

the array i'm trying parse looks this:

array [     array [     0: 'my_field1',     1: 'val1'     ],      array [     0: 'my_field2'     1: 'val2'     ],      array [     0: 'my_field3'     1: 'val1'     ] ] 

are there better ways same task? maybe shorter?

1. create empty array hold matches
2. loop through array. on each iteration...
   1. loop through matches array , check if item same value exists. if does, set matched flag.
   2. check if matched flag has been set
      1. if so, alert user
      2. if not add item matches.

---

var array = [     [ 'my_field1', 'val1' ],     [ 'my_field2', 'val2' ],     [ 'my_field3', 'val1' ],     [ 'my_field4', 'val2' ],     [ 'my_field5', 'val3' ] ], matches = [], match = false;  for(var = 0, j = array.length; < j; i++) {     match = false;     for(var k = 0, l = matches.length; k < l; k++) {         if(matches[k][1] == array[i][1]) {             match = true;         }     }     if(match) alert('duplicate!');     else matches.push(array[i]); }