CODEWITHSUNDEEP
javascript
user2534663
user2534663

Reputation: 21

How to validate a text field so it can only contain a four digit number

I've managed to validate my field so it is always four digits, but i need to validate so that it is always a number. I tried adding this block of code but it doesn't work properly.

if (!(document.ExamEntry.cand.value.match(numbers))) {
    msg += "Only use numeric characters \n";
    document.ExamEntry.cand.focus();
    document.getElementById('cand').style.color = "red";
    result = false;
}

This will allow four digit combinations like 9a9a or !2#3 etc. I added the "numbers" variable like this;

var numbers = /[0-9]/;

What is a better way of doing this validation?

Upvotes: 2

Views: 11644

Answers (2)

AntouanK
AntouanK

Reputation: 4968

Let's say you get your value here

var val = document.ExamEntry.cand.value;

Then if you want it to be something with 4 digits inside, just do this

var itIsNumber = /^\d{4}$/.test(val); // true if it is what you want

if you want it to be something with 1 to 4 digits inside, just do this

var itIsNumber = /^\d{1,4}$/.test(val); // true if it is what you want

more examples and details here --> Regular Expressions

Upvotes: 6

Lex Podgorny
Lex Podgorny

Reputation: 2930

/^[0-9]{4}$/ for four numbers

/^[0-9]*$/ for any amount of numbers

/^[0-9]+$/ for at least one number

Upvotes: 3

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