Access HTML form values in javascript

Question

Here is what I am trying to achieve, but for some reason, it does not work:

Javascript:

<script type="text/javascript">         
  function  calculate() {             
     var n1 = getElementById("1").value
     var n2 = getElementById("2").value
     var answer = n1+n2
     alert(answer)
  }
</script>

HTML:

<form id="form">
<input id="1" type="text" />
<input id="2" type="text" />
<input type="button onClick="calculate()" value="Go" />
</form>

I am not sure where I went wrong, Can someone help please?

dsgriffin · Accepted Answer · 2013-04-21 10:43:31Z

4

You shouldn't start ID's with numbers - in HTML4 and CSS it isn't allowed, in HTML5 it is allowed, but it's not good practice to do so.

Also, in this context it is illegal in HTML5 - as an ID starting with a number requires at least one letter afterwards.

So, firstly replace the numbered ID's with letters/words.

Apart from this, you need to fix the syntax errors mentioned below:

Replace getElementById("id").value with document.getElementById("id").value;

and also replace <input type="button onClick="calculate()" value="Go" />

with <input type="button" onClick="calculate()" value="Go" /> (notice there was a closing " missing for "button").

Here is a working jsFiddle.

Here is the code used in the jsFiddle:

Javascript:

function  calculate() {
   var n1 = document.getElementById("aItem").value;
   var n2 = document.getElementById("bItem").value;
   var answer = n1+n2;
   alert(answer);
}

HTML:

<form id="form">
   <input id="aItem" type="text" />
   <input id="bItem" type="text" />
   <input type="button" onClick="calculate()" value="Go"/>
</form>

edited Apr 21, 2013 at 10:43

answered Apr 20, 2013 at 18:41

dsgriffin

68.8k17 gold badges141 silver badges139 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Chris Moschini Over a year ago

@user125697 Interesting that starting IDs with numbers is allowed now in HTML5; however, the IDs here are still completely illegal in both CSS AND HTML5 - because HTML5 requires "at least one character" in IDs: w3.org/html/wg/drafts/html/master/dom.html#the-id-attribute

dsgriffin Over a year ago

@SamCreamer Hey! Feel free to accept my answer if it helped at all (check this for how to do it -meta.stackexchange.com/questions/5234/…), thanks so much!

DaveB · Accepted Answer · 2013-04-20 19:04:43Z

1

HTML:

<input id="val1" type="text" value="100" />
<input id="val2" type="text" value="200"/>
<input type="button" onclick="calculate()" value="Go" />

JavaScript:

function  calculate() {
          var n1 = +(document.getElementById("val1").value);
          var n2 = +(document.getElementById("val2").value);
          var answer = n1+n2;
          alert(answer);
         }

This will add the 2 numeric values entered rather than concatenating them.

answered Apr 20, 2013 at 19:04

DaveB

9,5584 gold badges43 silver badges68 bronze badges

Collectives™ on Stack Overflow

Access HTML form values in javascript

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related