Format Number in an Html5 Input Tag

I think you can try something like this:

input type="number" name="number" pattern="([0-9]{1,3}).([0-9]{1,3})" title="Must contain a decimal number">

see here

Added Plunkr: Plunker

It can be achieved using javascript with corner case handling using toLocaleString()

function getChange(){
  // 48 - 57 (0-9)
  var str1 = valueRef.value;
  if((str1[str1.length-1]).charCodeAt() < 48 || (str1[str1.length-1]).charCodeAt() > 57){
    valueRef.value = str1.substring(0,str1.length-1 );
    return;
  } 

 // t.replace(/,/g,'')
  let str = (valueRef.value).replace(/,/g,'');

  let value = +str;

  valueRef.value = value.toLocaleString();
}

Working Codepen Demo Link

function inputLimiter(e,allow) {
    var AllowableCharacters = '';

    if (allow == 'custom'){AllowableCharacters=' 1234567890.';}


    var k = document.all?parseInt(e.keyCode): parseInt(e.which);
    if (k!=13 && k!=8 && k!=0){
        if ((e.ctrlKey==false) && (e.altKey==false)) {
        return (AllowableCharacters.indexOf(String.fromCharCode(k))!=-1);
        } else {
        return true;
        }
    } else {
        return true;
    }
    
    }

<script src=""></script>
<script src=""></script>
<input type="text" id="NameCharacters" onkeypress="return inputLimiter(event,'custom')" value="" maxlength="4" /></p>

In Javascript. But this was as far as I got, will just leave this here for awhile, need to handle other stuffs.