JSFiddle - React, Tailwind, and code Playground

HTML

<tr>
   <td><label>Birthdate</label>
      <input type="text" placeholder="mm/dd/yyyy" name="birthdate" id="birthdate" maxlength="10"/>
   </td>
</tr>

JavaScript

var format = "mm/dd/yyyy";
var match = new RegExp(format
    .replace(/(\w+)\W(\w+)\W(\w+)/, "^\\s*($1)\\W*($2)?\\W*($3)?([0-9]*).*")
    .replace(/m|d|y/g, "\\d"));
var replace = "$1/$2/$3$4"
    .replace(/\//g, format.match(/\W/));

function doFormat(target)
{
    target.value = target.value
        .replace(/(^|\W)(?=\d\W)/g, "$10")   // padding
        .replace(match, replace)             // fields
        .replace(/(\W)+/g, "$1");            // remove repeats
}

$("input[name='birthdate']:first").keyup(function(e) {
   if(!e.ctrlKey && !e.metaKey && (e.keyCode == 32 || e.keyCode > 46))
      doFormat(e.target)
});