How to make an input accept only Binary numbers <input type="text" name="number"/>

Question

how do I make this field accept only binary numbers that do not accept 12 or 13 and etc, only numbers 1 and 0, as 0000111 or 1000 or 11111??

Answer 1

function SomenteNumero(e){
 var tecla=(window.event)?event.keyCode:e.which;
if((tecla==48 || tecla==49)) return true;
 else{
return false;
 }
 }

<input type="text" size="10" value=""' onkeypress="return SomenteNumero(event);">

• A function is a Javascript procedure - a set of instructions that executes a task or calculates a value. To use a function, you must define it somewhere in the scope you want to call it.
• The onkeypress event occurs when the user presses a key (on the keyboard) - in this case, calls the function.
• keycode (Keyboard Codes): Represents the number of the key the user presses on the keyboard 48 is the zero and 49 is the one.
• If (if) the key is zero or one, all right, it accepts (Return true)
• else (IS) does not accept.

I noticed that the keycode is now obsolete and will be discarded:

I tested with e.key

function SomenteNumero(e){
 var tecla=(window.event)?e.key:e.which;
if((tecla==48 || tecla==49)) return true;
 else{
return false;
 }
 }

<input type="text" size="70" value=""' onkeypress="return SomenteNumero(event);">

in modern browsers.