Comparing 2 input fileds values using jQuery

Question

I have 2 html input fields, one in disabled and gets value from a php file using jQuery ajax and the other one is filled by the user.

I made a jQuery script which compares these two fields and should show a message if the user input is greater than the ajax filled input. The problem is that it returns a strange result, for example if the ajax field is 12300 and the input field is 8 it shows the message, but if ajax is 12300 and the input is 12229 than it does not show the message.

$(document).ready(function(){
    $("#cantitate").blur(function(){
    var cant_ins = $("#cantitate").val();
    var cant_suger = $("#info_cantitate").val();
    if (cant_ins > cant_suger){
        $("#status_cant").text("Cantitatea depaseste disponibilitatea");
    }
        else
    {
        $("#status_cant").empty();
    }
        });
});

.val() from a input will return a string, not a number

atmd
– atmd

2015-02-03 09:21:30 +00:00
Commented Feb 3, 2015 at 9:21 — atmd
– atmd, Commented Feb 3, 2015 at 9:21

adeneo · Accepted Answer · 2015-02-03 09:21:29Z

3

You're comparing strings, not numbers, that's why you get strange results, 1200 would be less than 200 as the first one starts with the character 1 and the second one with 2 etc.

You can use parseInt for integers or parseFloat for floats to parse the strings as numbers, or you can just use the + sign to coerce the strings to numbers

$(document).ready(function(){
    $("#cantitate").on('blur', function(){
        var cant_ins   = +$("#cantitate").val();
        var cant_suger = +$("#info_cantitate").val();

        if (cant_ins > cant_suger){
            $("#status_cant").text("Cantitatea depaseste disponibilitatea");
        } else {
            $("#status_cant").empty();
        }
    });
});

answered Feb 3, 2015 at 9:21

adeneo

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4 Comments

atmd Over a year ago

love the + syntax for coercing strings

Ryan Over a year ago

@atmd it is actually "tricky" and will likely confuse people who have never seen it before, whereas parseInt(value, 10) would not likely lead to confusion.

adeneo Over a year ago

@self - well, they've seen it now. There's actually more issues with parseInt as people tend to forget the radix and get strange results, but generally I would have used parseInt in an answer, but the OP isn't clear on wether or not the inputs only accepts integers, or if floats are allowed as well

atmd Over a year ago

@self true, but then the same could be said for Ternary operators or decision tables. every aspect of coding can confuse people who haven't seen it before.

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