javascript multiple input textarea validation

Question

Hi.
I have 'n' numbers in a TEXTAREA on a form. After the user enters some value in the TEXTAREA, I need to validate it's not a duplicate of any other value.

Ex :

TEXTAREA_1 value =
10
20
30
40
10

It should alert and say 'value 10 was entered more than once'. Please help me with the Javascript.

Thank you so much.

Answer 1

pure DOM/JS solution:

  <form id="foo">
    <textarea id="numbers-textfield" cols=40 rows=20>10
    20
    30
    40
    50
    60
    60</textarea>
    <br>
    <input type=submit value=submit>
</form>
<script>
    (function() {
    var form = document.getElementById('foo'),
        textarea = document.getElementById('numbers-textfield'),
        inArray = function( value, arr ) {
     for ( var i = arr.length; i--; ) {
         if ( value == arr[i] ) {
      return true;
         }
     }
     return false;
        }


    form.onsubmit = function() {
        var value = textarea.value.split(/\s+/), len = value.length, stack = [], errors = false;


        for ( var i = 0; i<len; ++i ) {
     var isNum = !isNaN( value[i] );
     if ( !isNum ) { continue; }
     if ( errors ) { break; }
     if ( !inArray( value[i], stack ) ) {
         stack.push( value[i] );
     } else {
         errors = true;
         alert( value[i] + ' already in stack');
     }
        }

        if ( errors ) {
     return false;
        }

    }

    })();
</script>

Answer 2

$(function() {
  $("form").submit(function() {
    var txt = $("#TEXTAREA_1");
    var vals = txt.val().split("\n");
    var len = vals.length;

    for(var i = 0; i < len; i++) {
      for(var j = i + 1; j < len; j++) {
        if(vals[i] === vals[j]) {
          alert("Duplicate values are not allowed");
          txt.select();
          return false;
        }
      }
    }
  });
});

It works

Answer 3

var nums = textarea.value.split('\n').sort();
var prev;
for (var i = 0; i < nums.length; i++ ) {
    if (prev && nums[i] == prev) {
        alert('value ' + prev + ' was entered more than once');
        break;
    }
    prev = nums[i];
}