js various verification text box input formats (regular expressions)_form effects

Cannot be empty

Only English and numbers can be entered

Judgment characters are composed of letters, numbers, underscores, and periods. And the beginning can only be underscores and letters
/^([a-zA-z_]{1})([ w]*)$/g.test(str)

Only numbers can be entered

Only Chinese can be entered

Only English can be entered

Only Chinese, English, numbers, @ symbols and . symbols can be entered

Only English input is allowed, and neither paste nor pop-up of the paste menu is possible

Only numbers and periods can be entered (Note:The d in [^d.] cannot be written as a capital D, otherwise it will become all characters except numbers)

In short: first enter onkeyup="value=value.replace(/[^X]/g,'')" in and then X in (/[X]/g,'') Just replace it with the code you want to enter

Chinese: u4E00-u9FA5
Number: d, 0-9
English: a-z, A-Z
Other symbols@ , dot or other symbols. You can also have multiple, just separate them with
For example:
Chinese, English and numbers plus @ symbol plus dot symbol: a-zA-Z0-9u4E00-u9FA5@.

If you want to prevent the right-click pop-up menu and paste copied information in the text box, enter onKeyDown="fncKeyStop(event)" in the onpaste="return false" oncontextmenu="return false; "