I am performing date validation and now I am doing that user can only enter numbers ,/and backspace so now I want to add 2 more keys into my regular expression. I want to add delete and arrow keys so what will change I should do in my Regular Expression .This is my code

<input type="text" id="date" name="date" onkeypress="check(event,this);"  />

this is me Javascript code

<script type="text/javascript">

function check(evt, id)
{

 var value = id.value;

 var theEvent = evt || window.event;
 var key = theEvent.keyCode || theEvent.which;
 key = String.fromCharCode( key );

 var regex = /[0-9|\b|/]/;

 if( !regex.test(key)) 
 {
  theEvent.returnValue = false;

  if(theEvent.preventDefault) 
   theEvent.preventDefault();
 }   
}



</script>

Thanks waiting for your help.

I am performing date validation and now I am doing that user can only enter numbers ,/and backspace so now I want to add 2 more keys into my regular expression. I want to add delete and arrow keys so what will change I should do in my Regular Expression .This is my code

<input type="text" id="date" name="date" onkeypress="check(event,this);"  />

this is me Javascript code

<script type="text/javascript">

function check(evt, id)
{

 var value = id.value;

 var theEvent = evt || window.event;
 var key = theEvent.keyCode || theEvent.which;
 key = String.fromCharCode( key );

 var regex = /[0-9|\b|/]/;

 if( !regex.test(key)) 
 {
  theEvent.returnValue = false;

  if(theEvent.preventDefault) 
   theEvent.preventDefault();
 }   
}



</script>

Thanks waiting for your help.

• javascript
• jquery

• if you think you found the solution, check the notes I added in my answer they might help fixing your code to function as expected. – CME64 Commented Jun 18, 2013 at 9:05

3 Answers 3

You can skip the input validation if arrow, delete and backspace keys were pressed

function check(evt, id)
{

 var value = id.value;

 var theEvent = evt || window.event;
 var key = theEvent.keyCode || theEvent.which;

 // Don't validate the input if below arrow, delete and backspace keys were pressed 
 if(key == 37 || key == 38 || key == 39 || key == 40 || key == 8 || key == 46) { // Left / Up / Right / Down Arrow, Backspace, Delete keys
     return;
 }

 key = String.fromCharCode( key );
 var regex = /[0-9|/]/;

 if( !regex.test(key)) 
 {
  theEvent.returnValue = false;

  if(theEvent.preventDefault) 
   theEvent.preventDefault();
 }   
}

you should use on change and force change onkeyup to check the current value.

mistakes you have:

1- your regex should be the inverse, your current one checks if the value contains any of these but you want your value to not have other value.

2- you should escape the slash (/) character like this \/ so that it won't be assumed as the end of regex and the rest becomes modifiers!

Example:

document.getElementById('date').onchange = function(){
  var regex = /[^\d\/]/g;
  if(regex.test(this.value)) {console.log(false); return false;}
  else {console.log(true); return true;}
};

document.getElementById('date').onkeyup = function(){
  this.onchange();
};

DEMO

note: make sure you validate the whole date as dd/mm/yyyy or whatever your format is, right before sumission

Why don't you just check the actual value of the element, rather than the keypresses which create the value?

You can use the oninput event for that.