HTML pattern regex for no spaces

Question

What will be the correct regex pattern for an HTML input which should allow only Letters, digits and @/./+/-/_. No spaces.

Answer 1

You can use this regex for no space:

<form>
  <input type="text" pattern="[^' ']+" />
  <input type="submit" value="test submit">
</form>

So you can modify it to add your other rules

Answer 2

If characters order and count does not matter you can use this:

^[-a-zA-Z0-9@\.+_]+$