How to find the sum of variables in javascript?

Question

var pagenumber = localStorage["pageno"];
var sum = pagenumber + i;
display(sum);

In this case i am getting the output sum = 11 (when input pagenumber = 1 and i = 1) , But i require the output sum = 2

Both values _(or the first)_ aren't numbers but strings. `1 + 1 = 2` and `'1' + '1' = '11'`. Use `parseInt(localStorage["pageno"])` to parse it. — H. Pauwelyn, Feb 01 '18 at 17:04
Possible duplicate of [How to force JS to do math instead of putting two strings together](https://stackoverflow.com/questions/4841373/how-to-force-js-to-do-math-instead-of-putting-two-strings-together) — Sebastian Simon, Feb 01 '18 at 17:11
Possible duplicate of [How to increment a value at localStorage](https://stackoverflow.com/questions/11375433/how-to-increment-a-value-at-localstorage) — JJJ, Feb 01 '18 at 17:15

score 2 · Accepted Answer · answered Feb 01 '18 at 17:04

2

Need to parse the "1" in localStorage to an integer using the built in parseInt funtion:

var pagenumber = localStorage["pageno"];
var sum = Number.parseInt(pagenumber) + i;
display(sum);

answered Feb 01 '18 at 17:04

Kyle

score 0 · Answer 2 · edited Feb 01 '18 at 17:09

0

You can use parseInt to convert your strings to integers in JavaScript:

var sum = parseInt(localStorage["pageno"]) + parseInt(i);
display(sum);

edited Feb 01 '18 at 17:09

Sebastian Simon

answered Feb 01 '18 at 17:04

IamCavic

2 Answers2