[jquery] parseInt with jQuery

Can someone help me figuring out why the following jQuery code doesn't work? I want to return a integer from an user input.

var test = parseInt($("#testid"));

Thank you & bye!

This question is related to jquery

The answer is


var test = parseInt($("#testid").val(), 10);

You have to tell it you want the value of the input you are targeting.

And also, always provide the second argument (radix) to parseInt. It tries to be too clever and autodetect it if not provided and can lead to unexpected results.

Providing 10 assumes you are wanting a base 10 number.


Two issues:

  1. You're passing the jQuery wrapper of the element into parseInt, which isn't what you want, as parseInt will call toString on it and get back "[object Object]". You need to use val or text or something (depending on what the element is) to get the string you want.

  2. You're not telling parseInt what radix (number base) it should use, which puts you at risk of odd input giving you odd results when parseInt guesses which radix to use.

Fix if the element is a form field:

//                               vvvvv-- use val to get the value
var test = parseInt($("#testid").val(), 10);
//                                    ^^^^-- tell parseInt to use decimal (base 10)

Fix if the element is something else and you want to use the text within it:

//                               vvvvvv-- use text to get the text
var test = parseInt($("#testid").text(), 10);
//                                     ^^^^-- tell parseInt to use decimal (base 10)

var test = parseInt($("#testid").val());