使用javascript过滤输入类型编号

Question

How do I not allowed when typing "2" when first typing ? Is possible using JavaScript?

<input type="number"/>

Only "2" can not typing when start. Any body help? Thank you.

Answer 1

 $('input').keypress(function(evt) { if (evt.which == "2".charCodeAt(0) && $(this).val().trim() == "") { return false; } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="number"/>