Addition turns into concatenation

Question

var Height=  (rowData.length * 30) + PPPP.top + 10 ;

When i print this i get 9013510... instead of 90 +135+10 = 235. Why does mine turns into concatentaion instead of Addition.

Is PPPP.top a string, perhaps? – Anders Fjeldstad Jul 07 '11 at 10:27 — Anders Fjeldstad, Jul 07 '11 at 10:27

score 3 · Answer 1 · answered Jul 07 '11 at 10:27

3

You probably need to convert PPPP.top to a number, eg.

var Height = (rowData.length * 30) + parseFloat(PPPP.top) + 10;

answered Jul 07 '11 at 10:27

mqchen

score 2 · Answer 2 · edited Jul 07 '11 at 10:27

2

PPPP.top is probably a string. Try:

var Height=  (rowData.length * 30) + parseInt(PPPP.top, 10) + 10 ;

edited Jul 07 '11 at 10:27

Jakub Konecki

answered Jul 07 '11 at 10:27

James Allardice

+1 for specifying the radix when calling [parseInt](https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt). – Anders Fjeldstad Jul 07 '11 at 10:29

duncan · Accepted Answer · 2011-07-07T11:39:41.787

1

It's probably treating one of the values incorrectly as a string. Try using parseInt and see if that works:

var Height=  (rowData.length * 30) + parseInt(PPPP.top, 10) + 10;

edited Jul 07 '11 at 11:39

answered Jul 07 '11 at 10:28

duncan

haha, yes, maybe overkill! In fact as everyone else spotted it's really just the PPPP.top value that requires parseInt – duncan Jul 07 '11 at 11:39

Talha Ahmed Khan · Answer 4 · 2011-07-07T10:35:30.110

1

You can use parseInt for that.

var Height=  (rowData.length * 30) + parseInt(PPPP.top, 10) + 10 ;

I have changed radix to base 10.

edited Jul 07 '11 at 10:35

answered Jul 07 '11 at 10:28

Talha Ahmed Khan

2

parseInt should always be given the radix parameter if you want to avoid something like a user's input of 08 being turned into 0 – duncan Jul 07 '11 at 10:30
Yes, Thanks. But you know when validation will come into play we have to make sure that everything is ok. Here I just gave the hint how can you handle it. There could be many ways how you want your user input the value. – Talha Ahmed Khan Jul 07 '11 at 10:34

4 Answers4