Question

i am validating an input box value so that it should contain only digit,.,-,/ if at any time user type any thing accept allowed character, then only that character should get removed.

ex. if i typed initially 12/12/ then a, then only a should get removed from text box not whole string 12/12.

what i have tried so far.-

<input type="text" onkeyup="isValidDate(this);"/>
function isValidDate(f){ 
    var re =/^[\d\/\.-]+$/;
   if (!re.test(f.value)) { 
    alert("called");
    f.value = f.value.replace(/^[\d\/\.-]+$/g,"");
   }
 }

i am getting alert but un wanted value is not getting removed.

How i can do this using java script?

Answer 1

You should be able to add a return in front of the function call.

Then in the javascript return false if the character is unwanted.

Here is what I would do below.

<input type="text" onkeyup="return isValidDate(this);"/>
function isValidDate(f){ 
    var re =/^[\d\/\.-]+$/;
   if (!re.test(f.value)) { 
    alert("called");
//if you need to add a value instead that can also be done here
return false;
   }
 }

Here is code that I used to check that the key press was either a number or the decimal. It also alerts the user by setting the label field that is passed.

<input id='txtUPT' name='UPT' type='text' style='width: 70px' onKeyPress="return NumbersOnly(event, 'lblStatusUPT')">
<label id='lblStatusUPT' class='status'></label>
    function NumbersOnly(evt, label) {
        var status = document.getElementById(label);
        evt = (evt) ? evt : window.event;
        var charCode = (evt.which) ? evt.which : evt.keyCode;
        if (charCode == 46) {
            return true;
        }
        if (charCode < 48 || charCode > 57) {
            status.innerHTML = 'Numbers Only Please';
            return false;
        }
        status.innerHTML = '';
        return true;
    }