JavaScript add .00 automatically in text box -

i have 2 textboxes add value when onchange event fired. answer automatically shown on third textbox readonly. if answer whole number or has decimal of .00 displays without .00.

this code working on textbox can put value:

function deduc3(obj) {     var pagibig = document.getelementbyid('pagibig').value;     obj.value = parsefloat(obj.value).tofixed(2);     var deduc3 = parsefloat(pagibig)+parsefloat(document.getelementbyid('totaldeduc').value);     if (!isnan(deduc3)) {         document.getelementbyid('totaldeduc').value = deduc3;         netpay();     } } 

but can't make work on readonly textbox.

please me achieve this. thank in advance.

try in if block:

document.getelementbyid('totaldeduc').value = deduc3.tofixed(2); 

this make code like:

function deduc3(obj) {     var pagibig = document.getelementbyid('pagibig').value;     obj.value = parsefloat(obj.value).tofixed(2);     var deduc3 = parsefloat(pagibig)+parsefloat(document.getelementbyid('totaldeduc').value);     if (!isnan(deduc3)) {         document.getelementbyid('totaldeduc').value = deduc3.tofixed(2);         netpay();     } }