JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="t1" onkeypress="validate();">

JavaScript

function validate()
    {
      var s=t1.value;
      var res="";
      for(i=0;i<s.length;i++)
      {
        var ascii=s.charCodeAt(i);
        if(ascii<48 || ascii>57)
          res+=String.fromCharCode(ascii);  
      }
      t1.value=res;
    }