How to use comparison operator in Javascript for two input values

Question

I want to compare the two input values, just try in javascript, but it's not working fine. I'm using the following code

function check_closing()
{
var opening = $('#opening').val();
var closing = $('#closing').val();
if(opening > closing)
{
    alert('Opening is greater than Closing. Please enter the correct value');
    $('#closing').val('');
}
}

if the opening value input = 8541, closing value like = 8241 it's work fine, but if the closing is 954 it's not working. Please help.

Thanks in advance.

ZoidbergWill · Accepted Answer · 2014-04-22 11:23:30Z

4

You're comparing the strings instead of integers, so you need to convert the strings to integers. Since as strings, '8541' > '8241'

>>>'8541' > '8241'
true
>>>'954' > '8241'
true

>>>8541 > 8241
true
>>>954 > 8241
false

So you want:

function check_closing()
{
    var opening = parseInt($('#opening').val());
    var closing = parseInt($('#closing').val());
    if(opening > closing)
    {
        alert('Opening is greater than Closing. Please enter the correct value');
        $('#closing').val('');
    }
}

To add more to why exactly this happened, in case you're interested: Strings are compared character by character, iirc. So the '9' is greater than the '8' but the '8241' is less than '8541' because '2' is less than '5'.

edited Apr 22, 2014 at 11:23

answered Apr 22, 2014 at 7:19

ZoidbergWill

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3 Comments

user123444555621 Over a year ago

You mean '954' > '8241'

T.J. Crowder Over a year ago

"Since as strings, '8541' > '8241'..." As numbers, too.

ZoidbergWill Over a year ago

Yeah, whoops. Updating now. Both the comments meant that. I didn't get it originally. My bad.

T.J. Crowder · Accepted Answer · 2014-04-22 07:54:03Z

2

The values of input elements are always strings. To compare them as numbers, you must convert them to numbers. You can do that with:

parseInt if they're whole numbers and you want to specify the number base and stop parsing at the first non-numeric character

Example:
```
var opening = parseInt($('#opening').val(), 10);
// This is the number base, usually 10 ---^^^^
```

parseFloat if they're decimal fractional numbers

Example:

var opening = parseFloat($('#opening').val()); // Always base 10

The + if you want JavaScript to guess the number base, and give you NaN if there's a non-numeric character

Example:
```
var opening = +$('#opening').val();
//            ^---- it's hiding here
```

...and a few others.

edited Apr 22, 2014 at 7:54

answered Apr 22, 2014 at 7:18

T.J. Crowder

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Comments

Mad Angle · Accepted Answer · 2014-04-22 07:22:35Z

1

First of all you you need to convert the strings into integers

function check_closing(){
    var opening = parseInt($('#opening').val(), 10);
    var closing = parseInt($('#closing').val(), 10);
    if(opening > closing){
        alert('Opening is greater than Closing. Please enter the correct value');
        $('#closing').val('');
    }
}

answered Apr 22, 2014 at 7:22

Mad Angle

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Comments

Ja͢ck · Accepted Answer · 2014-04-22 11:25:27Z

0

Convert the strings to integers before comparison:

function check_closing()
{
    var opening = $('#opening').val();
    var closing = $('#closing').val();
    if(parseInt(opening) > parseInt(closing))
    {
        alert('Opening is greater than Closing. Please enter the correct value');
        $('#closing').val('');
    }
}

edited Apr 22, 2014 at 11:25

Ja͢ck

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answered Apr 22, 2014 at 7:20

Jameem

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