How to use radio on change event?

I have two radio button on change event i want change button How it is possible? My Code

<input type="radio" name="bedStatus" id="allot" checked="checked" value="allot">Allot
<input type="radio" name="bedStatus" id="transfer" value="transfer">Transfer

Script

<script>
    $(document).ready(function () {
        $('input:radio[name=bedStatus]:checked').change(function () {
            if ($("input[name='bedStatus']:checked").val() == 'allot') {
                alert("Allot Thai Gayo Bhai");
            }
            if ($("input[name='bedStatus']:checked").val() == 'transfer') {
                alert("Transfer Thai Gayo");
            }
        });
    });
</script>

You can use this which refers to the current input element.

$('input[type=radio][name=bedStatus]').change(function() {
    if (this.value == 'allot') {
        alert("Allot Thai Gayo Bhai");
    }
    else if (this.value == 'transfer') {
        alert("Transfer Thai Gayo");
    }
});

http://jsfiddle.net/4gZAT/

Note that you are comparing the value against allot in both if statements and :radio selector is deprecated.

In case that you are not using jQuery, you can use the document.querySelectorAll and HTMLElement.addEventListener methods:

var radios = document.querySelectorAll('input[type=radio][name="bedStatus"]');

function changeHandler(event) {
   if ( this.value === 'allot' ) {
     console.log('value', 'allot');
   } else if ( this.value === 'transfer' ) {
      console.log('value', 'transfer');
   }  
}

Array.prototype.forEach.call(radios, function(radio) {
   radio.addEventListener('change', changeHandler);
});

An adaptation of the above answer...

$('input[type=radio][name=bedStatus]').on('change', function() {
  switch ($(this).val()) {
    case 'allot':
      alert("Allot Thai Gayo Bhai");
      break;
    case 'transfer':
      alert("Transfer Thai Gayo");
      break;
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="radio" name="bedStatus" id="allot" checked="checked" value="allot">Allot
<input type="radio" name="bedStatus" id="transfer" value="transfer">Transfer

http://jsfiddle.net/xwYx9