JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="result" id="result" maxlength="4" />
	<button onclick="generate()">Generate</button>
	
	<p id="error"></p>
	<div id="zebra"></div>
	<div id="yeah"></div>
	<div id="ex"></div>
	<div id="weh"></div>	
	<p id="combo"></p>

JavaScript

function generate(){		
			var hello = document.getElementById("result").value;
			var numbers = /^[-+]?[0-9]+$/;
			if(!(hello.match(numbers))){
				document.getElementById("error").innerHTML = "Input Numbers Only!!!";
				document.getElementById("combo").innerHTML = "";
				document.getElementById("weh").innerHTML = "";
				document.getElementById("ex").innerHTML = "";
				document.getElementById("yeah").innerHTML = "";
				document.getElementById("zebra").innerHTML = "";				
			}else{
			document.getElementById("error").innerHTML = "";			
			var arr = [];
				
			//var hello = 6791;	
			var h = 0;
			
			var zRandom = 0;
			var zRandomRound = 0;
			var zRandomString = "";
			
			var yRandom = 0;
			var yRandomRound = 0;
			var yRandomString = "";
			
			var xRandom = 0;
			var xRandomRound = 0;
			var xRandomString = "";
			
			var wRandom = 0;
			var wRandomRound = 0;
			var wRandomString = "";
			
			var a = 0;
			var a2 = 0;
			var b = 0;
			var c = 0;
			var d = 0;
			var e = 0;
			var e2 = 0;
			var f = 0;
			var g = 0;
			
			// gagawing array yung hello	
			var arr = hello.toString(10).replace(/\D/g, '0').split('').map(Number);
			for(i=0;i<arr.length;i++) arr[i] = +arr[i]|0;
			
			//initialize variables 
			var z = arr[3];	
			var y = arr[2];
			var x = arr[1];
			var w = arr[0];
			
			while((((a2 <= 0) || (a2 > 49)) || ((b <= 0) || (b > 49)) || ((c <= 0) || (c > 49)) || ((d <= 0) || (d > 49)) || ((e2 <= 0) || (e2 > 49)) || ((f <= 0) || (f > 49)) || ((g <= 0) || (g > 49)  ))){
				
				//loop ulit kapag hindi match yung random number sa value nung z
				while( zRandomString != z){		
					 zRandom = Math.floor(Math.random() * (109 - 100 + 1)) + 100;
					 zRandomRound = zRandom % 10;
					 zRandomString = zRandomRound.toString();
				}
				var zNew = zRandom; //new value ng z
				document.getElementById("zebra").innerHTML = "Z = " + zNew + "<br />";// udsadsadsad
				
				h = zNew;
				
				while( yRandomString != y){		
					 yRandom =...