View Full Version : How to put a JavaScript variable into the value of a text box

03-26-2012, 03:45 PM
I have this code but it doesnt work:

<script type="text/javascript">
var number = 10;
document.getelementbyid(number).value = number;
<input type="text" id="number" value="">

Can anybody help me out here?

Philip M
03-26-2012, 04:32 PM
A lot of errors in so few lines!

a) You are using the same name/id for a Javascript variable and an HTML element.

b) Javascript is case sensitive so you must spell getElementById exactly as shown

c) The id of the textbox is a literal so must be in quotes. Without the quotes the reference is to the variable number, which has the value of 10, which is nonsense. (Just in case - an id must start with a letter).

d) Your script attempts to refer to the textbox before it exists.

<input type="text" id="mynumber" value="">

<script type="text/javascript">
var number = 10;
document.getElementById("mynumber").value = number;

Quizmaster: In astronomy, a nucleus, a coma and a tail are parts of which celestial body?
Contestant: A horse.

03-26-2012, 04:36 PM
Thanks works perfectly.

Sorry about the errors lol.


03-26-2012, 04:47 PM
There is an error in your syntax . Capital letters are important.

<script type="text/javascript">
var number1 = 10;
var number = document.getElementById("number");
// number.value = "Hello World"; // <-- This does not work jet.
<input type="text" id="number">

But I could not assign the value jet.

Philip M
03-26-2012, 05:19 PM
clausrei -

Note that in Internet Explorer, names and id's are global variables and thus you should NEVER use a (global) variable or function name which is the same as an HTML element name or id. Example:-

<input id = "text">

<script type = "text/javascript">
text = "Hello World"; // global variable
document.getElementById('text').value = text;

I agree that the variable here is local because it is declared with the var keyword. But you are playing with fire! Follow my simple rule.