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

Question

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

Answer 1

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