How can val() return Number?

Question

In the valdocs written this description:

.val() Returns: String, Number, Array

I tried to get a Number, but it seems to return string only, Is there something that I'm doing wrong?

$('#gdoron').val('1');

alert($('#gdoron').val() === '1'); // true 
alert(typeof $('#gdoron').val());  // string.

$('#gdoron').val(1);

alert($('#gdoron').val() === 1);  // false
alert(typeof $('#gdoron').val()); // string (not "number"!)

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="gdoron" />

My question is: how can val() return number as the docs says? The question is not about how can I parse the string.

​

Solution 1

Some HTML5 elements e.g. progress;

console.log(typeof $("#prog").val()); // number 

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<progress value="50" max="100" id="prog"></progress>

Solution 2

A text input's value attribute will always return a string. You need to parseInt the value to get an integer:

parseInt($('#myInput').val(), 10);

Solution 3

I've done a bit of quick peeking around, and I think I have an answer. If you look at the implementation of the val function you can see that if a so-called val-hook is in place, if the val-hook returns a number, that number will be returned as-is from the val function. I found this discussion which suggests that val-hooks are primarily used by plugins to create custom controls, such as sliders, etc., where the "natural" return value of val could be an integer. Hope this sheds a bit of light on your question.

Solution 4

Hmm. For all these in the console, jQuery $($0).val() and Javascript's $0.value return the string "3":

<input type='number' value='3'/>
<input type='text' value='3'/>
<input type='radio' value='3'/>
<input type='checkbox' value='3'/>

So I think the jQuery val() documentation could be clearer. I can't see how it would ever return a number value so I'd suggest using parseInt($($0).val()) or parseFloat($($0).val()).

Solution 5

You could simply create a jquery plugin to use instead of val() that would do this. Here I create the function nval() to use instead of val() when fetching a elements value.

$.fn.nval = function() {
   return Number(this.val())
};

Then in your code just use the following to get the value as a number

$('#elementID').nval()

View more solutions

Comments

[gdoron is supporting Monica]

I know that, I'm asking how can val return number as the docs says, not how can I parse the string.

[Felix Kling]

Also see the HTML5 draft (the return value is double).

[Felix Kling]

@gdoron: It says: [...] form elements such as input, select and textarea [...]. Now, I'm not a native English speaker, but it sounds to me that this is not meant to be an exhaustive list.

[gdoron is supporting Monica]

Something weird: alert($("#prog").val() === 50​)​;​​​​​​​​​​//false​​ and alert($("#prog").val() === '50')​; //false​​​​​​​​​​​​. HOW?

[pimvdb]

It looks like it returns a number by default. $("<progress value='50' max='100'>").get(0).value === 50.

[Glenn]

The first link is broken.

[gdoron is supporting Monica]

While correct, it doesn't answer the (very old) question.

[carcus88]

Sure thats true but its provides a way to do it thats safe. If you really want to do it just use a plugin that overrides val() like $.fn._val = jq.fn.val; $.fn.val = function(value) { if ( !arguments.length ) { var v = this._val(); if(!isNaN(+v)) { return Number(v); } return v; } else { return this._val(value); } };

[gdoron is supporting Monica]

Dude, the question is not how to overcome a problem, simply trying to understand how jQuery itself can return a Number as the doc says. And you can see the accepted answer showing why they wrote it, <progress> for example returns a Number natively!.

[Gibin Ealias]

Using the unary operators -, + and ~ before the $ will also return a number. +$('#gdoron').val();