How to make 1 + 1 = 2 instead of 1 + 1 = 11

Question

I am trying to add the number mathematically, but it keeps adding the number after it.

It takes the id number (begen), then it gets the number inside another div (kacbegen).

var begen = $(this).attr('id');
var kacbegen = $("#math" + begen).text();
var toplam = (kacbegen + 1);

alert(toplam);

However, when doing the math (toplam), it alerts all the numbers.How to add the number mathematically ?

Jai · Accepted Answer · 2015-12-14T10:26:09.013

7

Convert it to number via adding a +:

var toplam = (+kacbegen + 1);

Unary plus (+)

The unary plus operator precedes its operand and evaluates to its operand but attempts to converts it into a number, if it isn't already.

edited Dec 14 '15 at 10:26

answered Dec 14 '15 at 10:18

Jai

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This I didn't know!, will this method work only for `integer` or `floating` numbers also? – Bharadwaj Dec 14 '15 at 10:19
quite true but as far as numbers are concerned this would do @Bharadwaj – Jai Dec 14 '15 at 10:20
Clearest answer ever. Thanks! – user198989 Dec 14 '15 at 10:20
this will call `parseFloat` internally? because `parseFloat` will convert in weird way for some floating values. – Bharadwaj Dec 14 '15 at 10:21
@user198989 And by the way, neither protect from getting a `NaN`, so make sure you handle this case as well. – axelduch Dec 14 '15 at 10:21
@Bharadwaj I was wrong `+('1x')` would give `NaN` whereas `parseFloat('1x')` would give `1`, so they're not the same after all, so `parseFloat` is safer, in a way. – axelduch Dec 14 '15 at 10:23
@axelduch hmm, need to try with this method sometime. And thanks for clarifying – Bharadwaj Dec 14 '15 at 10:24

score 2 · Answer 2 · answered Dec 14 '15 at 10:19

It looks like you're working with Strings (and thus a + b is the concatenation operator) when you want to be working with Number (so x + y would be addition)

Perform your favorite way to cast String to Number, e.g. a unary +x

var kacbegen = +$("#math" + begen).text();

score 1 · Answer 3 · answered Dec 14 '15 at 10:17

You need to use parseInt to convert kacbegen, which is a String instance, to a Number:

var begen = $(this).attr('id');
var kacbegen = $("#math" + begen).text();
var toplam = (parseInt(kacbegen) + 1);

alert(toplam);

The + operator, when used with a String on either side, will serve as a concatenation, calling Number.prototype.toString on 1.

score 1 · Answer 4 · answered Dec 14 '15 at 10:17

1

You need to cast the contents to a number:

var contents = $("#math" + begen).text();
var kacbegen = parseFloat(contents);

answered Dec 14 '15 at 10:17

axelduch

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score 1 · Answer 5 · answered Dec 14 '15 at 10:19

1

You use kacbegen as a string. Please use as a integer use parseInt(kacbegen) + 1

answered Dec 14 '15 at 10:19

Bhavik Jani

180
7

How to make 1 + 1 = 2 instead of 1 + 1 = 11

5 Answers5

Unary plus (+)

Linked

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