How to validate a string without Reg ex - Javascript

Question

Im trying to finish up an assignment; here's what Im stuck at:

User input can only contain the following allowed characters

alphabetic characters lower case (a-z) upper case (A-Z)
apostrophe (‘)
hyphen (-)
Must have at least 1 alphabetic characters (a-z) (A-Z)

Note: You cannot make use of Reg Ex.

I can't really see another way of doing this without use of Reg Ex; Here what I've done so far...

function validate_name() {
   var name = document.getElementById("name").value;
   name = name.trim();
   for (i = 0;i < name.lenght; i++) {
      if (name.charAt(i) == a...I don't know what I'm doing

Any specific reason why RegEx cannot be used ?

Dinesh Chitlangia
– Dinesh Chitlangia

2015-08-17 05:56:48 +00:00
Commented Aug 17, 2015 at 5:56 — Dinesh Chitlangia
– Dinesh Chitlangia, Commented Aug 17, 2015 at 5:56

Guy · Accepted Answer · 2015-08-17 06:08:45Z

1

You can do something like that:

var str = prompt('Enter input:');
var alphaExist = false;
var valid = true;
for (var i = 0; i < str.length; i++) {
    if ("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'-".indexOf(str.charAt(i)) == -1) {
        valid = false;
    }
    if ("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".indexOf(str.charAt(i)) > -1) {
        alphaExist = true;
    }
}
alert(valid && alphaExist ? 'Valid' : 'Invalid');

http://jsfiddle.net/4wwod65h/

answered Aug 17, 2015 at 6:08

Guy

1,6173 gold badges19 silver badges31 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

gor181 · Accepted Answer · 2015-08-17 06:02:44Z

0

Have a look at the keycode list at: http://www.cambiaresearch.com/articles/15/javascript-char-codes-key-codes

Do not use

document.getElementById("name").value;

Rather parse an event triggered by keystrokes. You have a nice example of how to use this on MDN page: https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode

So combine the keycode list and the keyboard event to filter the keycodes you are interested in.

Hint: You are able to use a range as keycodes are bunch of numbers.

answered Aug 17, 2015 at 6:02

gor181

2,0682 gold badges15 silver badges12 bronze badges

Collectives™ on Stack Overflow

How to validate a string without Reg ex - Javascript

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related