JSFiddle - React, Tailwind, and code Playground

HTML

<input name=x size=10 maxlength=10  onkeyup="this.value=this.value.replace(/^(\d\d)(\d)$/g,'$1/$2').replace(/^(\d\d\/\d\d)(\d+)$/g,'$1/$2').replace(/[^\d\/]/g,'')">