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 conca

Answer 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;