How to make an addition instead of a concatenation

Question

I have an input button. I created for this input an attribute called "multiplicateur" which has the value of 1. When the button is clicked I have a .click() triggered. The function is suppose to get the value of the attribute and add 1 to it. So my output should be 2. Instead the output is 11. It seems the system makes a concatenation instead of an addition.

My HTML:

<input id="envoyer" type="submit" multiplicateur=1>

My JS:

$('#envoyer').click(function() {
    var ajaxData = $(this).attr('multiplicateur');
    alert(ajaxData + 1);
});

Alex · Accepted Answer · 2020-09-30T17:16:54.780

21

ajaxData is a string. Thus, you need to parse it to an integer...

 $('#envoyer').click(function() {
    const ajaxData = $(this).attr('multiplicateur');

    /* parse string to integer */
    alert(parseInt(ajaxData) + 1);

});

edited Sep 30 '20 at 17:16

answered Jan 31 '12 at 14:56

Alex

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You code works but when i test it in JS Fiddle it returns an error (Missing radix parameter). Do you know why? – Marc Jan 31 '12 at 15:04
@user1162116 It's intriguing your to receiving that error as the second parameter to `parseInt` is optional. Try passing 10 - `parseInt(ajaxData, 10)` – Alex Jan 31 '12 at 15:26
No error know! Great. What does the second parameter represent? – Marc Jan 31 '12 at 15:34
@user1162116 the second parameter is the ***radix*** or ***base*** (number of unique digits). I assumed you wanted the common *base 10* – Alex Jan 31 '12 at 17:25

score 3 · Answer 2 · answered Jan 31 '12 at 14:56

3

You have to parse it first:

    parseInt(ajaxData)+1;

answered Jan 31 '12 at 14:56

Sören Titze

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31

score 1 · Answer 3 · answered Jul 14 '14 at 08:33

1

In order to add value with decimal point, please use parseFloat(ajaxData)

alert(parseFloat(ajaxData) + 1);

answered Jul 14 '14 at 08:33

Muhammed Shihabudeen Labba A

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score 0 · Answer 4 · answered Mar 16 '19 at 09:58

0

For substracting

function removeFromQtt(){
             $("qty").value = parseInt($("qty").value)-1;
 }

For addition

function add(){
             $("qty").value = parseInt($("qty").value)+1;
 }

answered Mar 16 '19 at 09:58

Ahmed Adewale

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19

How to make an addition instead of a concatenation

4 Answers4

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