JSFiddle - React, Tailwind, and code Playground

JavaScript

function IsNumeric(input)
{
    return (input - 0) == input && (input+'').replace(/^\s+|\s+$/g, "").length > 0;
}

var i = '1234';
var ii = '1234';
var iii = '1234';
var iiii = '1234';

if (IsNumeric(i) && IsNumeric(ii) && IsNumeric(iii) && IsNumeric(iiii)) 
    alert('All Numeric');
else
    alert('Not All Numeric');