How to prevent keypress two digits after a decimal number?

Monica picture Monica · Mar 28, 2013 · Viewed 30.8k times · Source

I have got a task to prevent keypress two digits after a decimal number. My jquery file is

$(function(){ 
    $('#name').bind('paste', function(){
    var self = this;
    setTimeout(function() {
        if(!/^[a-zA-Z]+$/.test($(self).val()))
            $(self).val('');
    }, 0);    
           }); 

        $('#salary').bind('paste', function(){
    var self = this;
    setTimeout(function() {
        if(!/^\d*(\.\d{1,2})+$/.test($(self).val()))
            $(self).val('');
    }, 0);    
           }); 

    $('.decimal').keyup(function(){
        var val = $(this).val();
        if(isNaN(val)){
             val = val.replace(/[^0-9]./g,'');


             if(val.split('.').length>2) 
                 val =val.replace(/\.+$/,"");
        }
        $(this).val(val); 
    });
    });      

My html page is

<b>Name</b>
<input type="text" id="name"  /><br/>
<b>Salary</b>
<input type="text" id="salary"  class="decimal" />

here i want only write 2 digits after decimal,how can i do this? You can see my code in http://jsfiddle.net/V6s4B/

Answer

Daniel Imms picture Daniel Imms · Mar 28, 2013

You can handle the key event before keyup on keypress, if the input is not to our liking we can disable the event from occurring. Something like this:

Update

Unfortunately my original answer below fails on certain numbers that can't be represented accurately as a float. Here is another solution that checks the position of the '.' character against the length of the string with a handy helper function.

jsFiddle

$('.decimal').keypress(function (e) {
    var character = String.fromCharCode(e.keyCode)
    var newValue = this.value + character;
    if (isNaN(newValue) || hasDecimalPlace(newValue, 3)) {
        e.preventDefault();
        return false;
    }
});

function hasDecimalPlace(value, x) {
    var pointIndex = value.indexOf('.');
    return  pointIndex >= 0 && pointIndex < value.length - x;
}

Original answer

jsFiddle

$('.decimal').keypress(function (e) {
    var character = String.fromCharCode(e.keyCode)
    var newValue = this.value + character;
    if (isNaN(newValue) || parseFloat(newValue) * 100 % 1 > 0) {
        e.preventDefault();
        return false;
    }
});

Note that parseFloat(newValue) * 100 % 1 > 0 evaluates to true if newValue contains a number that has more than 2 decimal places.