addition problem

[rejisha]

i have two text boxes with the id as first and second respectively.In javascript i took the values using

var first=document.getElementbyId("first").value.
var second=document.getElementbyId("second").value.
var sum=first+second;

But the problem is when i alert the sum i got the result as concatenated.i didn't get the original sum.I also tried it as first=Number(first) , but there is no result.

can u help me?
thanx in advance

[Shanti C]

var1=document.getelementbyid('txt1').value
var2=document.getelementbyid('txt2').value
var3=Number(var1)+Number(var2)

or concentrate on eval() function in javascript by googling....

[nav33n]

You should use parseInt.

var1=document.getelementbyid('txt1').value;
var2=document.getelementbyid('txt2').value;
var3=parseInt(var1)+parseInt(var2);
alert(var3);

[Troy III]

...
var3 = parseFloat(var1)+parseFloat(var2);
alert(var3);

Will do also fine. This additionally ensures that values like: 1.356 + 6.32 don't get rounded into a sum of say 7, so you get the correct value of 7.676 ...

Regards @all

[~s.o.s~]

> concentrate on eval() function in javascript by googling

As in concentrate on swatting a fly with a hammer? eval sort of fires off a mini-compiler which dynamically evaluates the string passed to it. Look for better ways of doing things and use eval only when required. E.g. when evaluating a random expression entered by the user when creating a calculator application in Javascript.

> You should use parseInt .

Surprise surprise!

parseInt("09") + parseInt("09")

Moral: Always specify the base when using parseInt .

> This additionally ensures that values like: 1.356 + 6.32 don't get rounded into a sum of
> say 7, so you get the correct value of 7.676

I would still stay away from all those parseXXX variations since they give results which you least expect.

alert(parseFloat("1asldfjas"));
alert(Number("1asdfsdf"));

[Troy III]

The question was, I believe, "how to make sure he is summing numbers instead of symbols of their presentation?". alert(parseFloat("1asldfjas")); will yield a number as expected. In this case: 1; [but no other order will!] the opposite will return NaN [not a number] thing.

Although, your reply was rich and informative till this point, I'd still like to know what was your suggested solution to this problem?

Regards.

p.s.:
I'm totally aware that validating input before anything else is always the safest way to go.

[~s.o.s~]

My suggested solution was to use the Number constructor so as to perform addition as well as validation in a single go. But some additional validation will always be required to prevent inputs like 1E2 creeping through and giving unexpected results.