gripen fighter gripen fighter - 25 days ago 7
HTML Question

Allow html input box to only enter one full number and exactly decimal .5

I'm making web application that requires users to enter number with one decimal place. I restrict users from entering other characters that numbers from using this javascript code


<input type="number" name='days' class="w3-input w3-padding-tiny" id="cntday" onkeypress="return isNumberKey(event)" placeholder="Enter days"/>


function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : evt.keyCode;
if (charCode != 46 && charCode > 31 &&
(charCode < 48 || charCode > 57))
return false;
return true;

but this function only prevent users from entering characters other than numbers.
I need to prevent users from entering more than one decimal places as well as entered decimal should be .5

it's like this

  • if user enter 5.55 it should replace with 5.5 OR prevent user to input additional decimal

  • and if user enter 5.2 OR any decimal it should be replace with 5.5 in other words users should only able to enter number with decimal .5

how can I achieve this with my current onkeypress function ?

This is NOT a duplicate of the other question. Stop flagging this


Use this

$('#cntday').keyup(function() {
    if(this.value %1 != 0.5){
        this.value = this.value - this.value%1 + 0.5;

The condition checks whether a decimal has been entered or not and as soon as a decimal is entered and a number is entered it changes it to .5 It fulfills both the requirements you mentioned. Check it here