addition in javascript

i made 2 textbox, the first textbox has a value of 12 and the other one is 20, when i click on the button result, my result textbox displays 1220, what should i do in order for my result textbox to display 32?

 

Use parseInt() when calculating the result. Now the script is concatinating the input from the textboxes, cause they are parsed as strings. Something like that:

result.value = parseInt(textbox1.value)+parseInt(textbox2.value);

Code (markup):

 

anyway, is there a way where i can lock a textbox. where in a user cannot type a string. if the user type a string, the value of the textbox will be null?

thanks

 

parseInt is corect, but wen i inputted 1.50, the result textbox dispalys 1 instead of 1.50! is there anyway to fix this?
thank you so much!

 

Not quite sure i understand you, but i'll explain some stuff anyway. to lock the textbox use the following:

document.getElementById('mytextbox').disabled = 'disabled';

Code (markup):

Be aware that disabled input fields will not be send when a form is submitted. This could cause you some trouble too.
Here's a little method i'd use to limit the user to typing numbers only:

<script type='text/javascript'>
function checkInput(str)
{
        if(isNaN(str))
                return str.replace(/[^0-9]+/g,'');       
        else
                return str;
}
</script>
<input type='text' onkeyup='this.value = checkInput(this.value)'>

Code (markup):

 

Yes, use parseFloat() insted. parseInt returns integers, parseFloat returns floating point numbers.