Adding two variables in js

Question

I am not sure why, but I am having a serious issue trying to add 1 to a variable.

    net = $('#net').val()+1;
$('#net').val(net).change();

This results in 1 1 (I understand that this is just concatenating). The last line is to output it to my input field. if I do this:

    net = net+1;
$('#net').val(net).change();

I get NaN. When I try to use parseInt like this:

    net = net+1;
net = parseInt(net,10);
$('#net').val(net).change();

I still get NaN. Ihave looked at the other examples on SO that adress this problem, and they say to use parseInt(), which I did. What else can I try to get this to add 1 to the existing number and putit in my field?

What's the result of parseInt($('#net').val()) + 1

vc 74
– vc 74

2013-05-22 13:12:32 +00:00
Commented May 22, 2013 at 13:12 — vc 74
– vc 74, Commented May 22, 2013 at 13:12

AGuyCalledGerald · Accepted Answer · 2013-05-22 13:26:49Z

4

try to do net = parseInt(net,10); first

then net = net+1;

In your code you do:

net = net+1; //from this point net=11
net = parseInt(net,10);

which is wrong, You should inverse your two statements

net = parseInt(net,10); //here net=1 (integer representation)
net = net+1; // the '+' between two integers will result in an addition and not a concatenation

edited May 22, 2013 at 13:26

AGuyCalledGerald

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answered May 22, 2013 at 13:12

0x1gene

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2 Comments

Andrew Over a year ago

parseInt(net, 10) is the best answer so far, because it prevents odd edge cases where strings like "011" could be interpreted as 9

Jim Over a year ago

This is the one that finally did the trick. Thanks to ALL for your assistance and answers.

tymeJV · Accepted Answer · 2013-05-22 13:19:25Z

3

Try this:

net = +net + 1;
$("#net").val(net);

The + in front of your net variable casts this to a Number

Fiddle: http://jsfiddle.net/tymeJV/WudHW/1/

edited May 22, 2013 at 13:19

answered May 22, 2013 at 13:11

tymeJV

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3 Comments

Jim Over a year ago

Still get NaN. Does the double quuotes make a difference?

Mr_Green Over a year ago

@Jim keep a break point in your favourite browser developer tool and check where the problem is arising.

tymeJV Over a year ago

@Jim -- Before you do any math, can do do a quick alert(net) and verify that the net variable actually contains data?

Modestas Stankevičius · Accepted Answer · 2013-05-22 13:12:05Z

1

var a = parseInt($('#net').val())+1

$('#net').val(a).change();

this should help.

answered May 22, 2013 at 13:12

Modestas Stankevičius

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Comments

benzonico · Accepted Answer · 2013-05-22 13:12:38Z

0

Thing is your variable net is not a number but a string, you have to first parse it to an int :

net = parseInt($('#net').val());

And then do all the add you want.

answered May 22, 2013 at 13:12

benzonico

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Comments

Shijin TR · Accepted Answer · 2013-05-22 13:15:14Z

0

Use parseInt

     net = parseInt($('#net').val())+1;
     $('#net').val(net).change();

edited May 22, 2013 at 13:15

answered May 22, 2013 at 13:13

Shijin TR

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Comments

samuke · Accepted Answer · 2013-05-22 13:17:37Z

0

It is because val() returns a string and you try to add 1 to a string, which contains number 1 and a space letter. Try for example

var net = +$.trim($('#net').val());
$('#net').val(net + 1).change();

This gets rid of the white space and casts net as a number before inserting it back to the input(?) field.

answered May 22, 2013 at 13:17

samuke

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