How do I add an integer value with javascript (jquery) to a value that's returning a string? - Stack Overflow

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I have a simple html block like:

<span id="replies">8</span>

Using jquery I'm trying to add a 1 to the value (8).

var currentValue = $("#replies").text();
var newValue = currentValue + 1;
$("replies").text(newValue);

What's happening is it is appearing like:

81

then

811

not 9, which would be the correct answer. What am I doing wrong?

I have a simple html block like:

<span id="replies">8</span>

Using jquery I'm trying to add a 1 to the value (8).

var currentValue = $("#replies").text();
var newValue = currentValue + 1;
$("replies").text(newValue);

What's happening is it is appearing like:

81

then

811

not 9, which would be the correct answer. What am I doing wrong?

• javascript
• jquery
• casting

Share Improve this question Follow asked Jan 20, 2009 at 5:07 rballrball 6,95577 gold badges5151 silver badges7878 bronze badges

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11 Answers 11

Sorted by: Reset to default 189

parseInt() will force it to be type integer, or will be NaN (not a number) if it cannot perform the conversion.

var currentValue = parseInt($("#replies").text(),10);

The second paramter (radix) makes sure it is parsed as a decimal number.

The integer is being converted into a string rather than vice-versa. You want:

var newValue = parseInt(currentValue) + 1

Parse int is the tool you should use here, but like any tool it should be used correctly. When using parseInt you should always use the radix parameter to ensure the correct base is used

var currentValue = parseInt($("#replies").text(),10);

parseInt didn't work for me in IE. So I simply used + on the variable you want as an integer.

var currentValue = $("#replies").text();
var newValue = +currentValue + 1;
$("replies").text(newValue);

In regards to the octal misinterpretation of .js - I just used this...

parseInt(parseFloat(nv))

and after testing with leading zeros, came back everytime with the correct representation.

hope this helps.

to increment by one you can do something like

  var newValue = currentValue ++;

Simply, add a plus sign before the text value

var newValue = +currentValue + 1;

Your code should like this:

<span id="replies">8</span>

var currentValue = $("#replies").text();
var newValue = parseInt(parseFloat(currentValue)) + 1;
$("replies").text(newValue);

Hacks N Tricks

var month = new Date().getMonth();
var newmon = month + 1;
$('#month').html((newmon < 10 ? '0' : '') + newmon );

I simply fixed your month issue, getMonth array start from 0 to 11.

You can multiply the variable by 1 to force JavaScript to convert the variable to a number for you and then add it to your other value. This works because multiplication isn't overloaded as addition is. Some may say that this is less clear than parseInt, but it is a way to do it and it hasn't been mentioned yet.

You can use parseInt() method to convert string to integer in javascript

You just change the code like this

$("replies").text(parseInt($("replies").text(),10) + 1);

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