javascript limit text input characters

Question

I am wanting to restrict the input characters for a text box to [a-z0-9_-]. However whenever if do this buttons like backspace and the arrow keys don\'t work. I have found s

Answer 1

Just change the regex in the example to something like this:

numcheck = /[^a-z0-9_-]/;

Or better yet, avoid the double negative with:

numcheck = /[a-z0-9_-]/;
return numcheck.test(keychar);

Then you can look up the keycodes of backspace, etc. and check for them too:

if (keychar === 8) return true;
...

Or even put them in your regex:

numcheck = /[a-z0-9_\x08-]/;