CODEWITHSUNDEEP
javascriptjqueryhtml
Kunal Vashist
Kunal Vashist

Reputation: 2471

validation on input box

I want to create a Input Box for entering the private entering details of a person, On which first character has to be A or E and rest can be alphanumeric and no special character are allowed. I need to do validation for the same that no one enter any special character and First character has to be A or E (all has to be check on the client side)

Can any one guide me how to proceed

Upvotes: 0

Views: 978

Answers (3)

Jukka K. Korpela
Jukka K. Korpela

Reputation: 201588

This sounds like a homework assignment (since starting with specifically “E” or “A” sounds very artificial), so I’d suggest first deciding on the interpretation of the task. Should “E” and “A” be interpreted case-insensitively? What exactly does “alphanumeric” mean? For example, is “Σ” or “Я” or “١” alphanumeric? If the purpose is to do the checks client-side, should you try to make the page completely non-functional when JavaScript is disabled, or should you just do the checks client-side as far as possible? (In the latter case, consider using the pattern attribute in HTML. On some modern browsers, it causes the check to be performed even when JavaScript is disabled.)

Upvotes: 0

primavera133
primavera133

Reputation: 1314

If this is the only field to validate I would write my own with js & regexp as Leonard Challis wrote (but on the keyup event).

If there will be a lot of fields and perhaps multiple forms on the site, I would consider a framework. This is pretty good: http://bassistance.de/jquery-plugins/jquery-plugin-validation/

If you would be using that one you could write a custom function for your special needs. http://docs.jquery.com/Plugins/Validation/Validator/addMethod#namemethodmessage

Upvotes: 0

LeonardChallis
LeonardChallis

Reputation: 7783

Look in to regex with JavaScript, along with the keydown event. You can attach a function to the keydown event, and inside this function check the input box(es) match and then proceed as you wish.

Something like this: (not tested)

<script>
function checkInput() {
  var inputToCheck = document.getElementById('my_input');
  if (!inputToCheck.value.match(/[AE]\w+/)) {
    // do something here, like alert them or remove special characters with .replace
  }
}
</script>

<input id="my_input" onkeydown="checkInput();" />

Upvotes: 2

Related Questions