How to use radio on change event?

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);
});