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 binations 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?

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 binations 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?

• javascript

• 4 The regular expression is wrong. "Four digits and nothing else" is /^[0-9]{4}$/. What you have now is "at least one digit anywhere in the input". – Jon Commented Jun 29, 2013 at 13:36
• This is GCSE assessed work, going towards a formal qualification. No help should have been asked for in this way. I don't know the exact rule around the qualification, but I suspect this is against them. – GKFX Commented Aug 12, 2013 at 13:52
• EDIT: Sorry, I just remembered you can ask IT sources for help. It's fine (I think.). – GKFX Commented Aug 12, 2013 at 13:59

2 Answers 2

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

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

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

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