Remove special characters from input field

Question

I've been searching everywhere but have been unable to find exactly what I am looking for.

I have an html form that is filled out with Mac addresses from our inventory so the strings inputted into the input field will look like:

A1:A2:A3:A4:A5:A6

I'm trying to write a script to remove the : character plus any spaces anywhere. That way when it is entered the output will be:

A1A2A3A4A5A6

This is what I have so far:

<input type="text" id="macaddress" onChange="removeChar();WriteLog();" />

Then in my script I have:

function removeChar() {
  var a = document.getElementById("macaddress").value;
  a = a.replace(/: /g, '');
  document.getElementById.innerHTML = a;
}

I don't get any JavaScript errors with this but nothing happens.

I also have another script that pulls the value of the field into a work log which is the other function WriteLog().

Essentially I want to remove the : then have the new value pulled into the log by the second function.

Answer 1

If you want to keep only numbers and letts you can use this

a.replace(/[^a-zA-Z0-9]/g, '');

which basically replaces everything that isn't a-z or A-Z or 0-9 with an empty string.

A great tool for explaining regex and testing it is Regex101

And this line document.getElementById.innerHTML = a; should be fixed as well, you probably meant something like document.getElementById('some-elements-id').innerHTML = a;

Answer 2

Question spec says you want to remove : and : with space. Make the space in the regex optional:

a = a.replace(/:( )?/g, '');

But you also need to account for preceeding spaces:

a = a.replace(/( )?:( )?/g, '');

I would also trim the initial string (Just good practice)

a = a.trim().replace(/( )?:( )?/g, '');

Finally, I am not sure what this line does: document.getElementById.innerHTML = a;, but that line will throw an error. Remove it.