import script in web worker

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>Time Web Worker Demo</title>
</head>
<body>
<h1 id="resultContainer"></h1>
<input type="number" id="number1" value="7" placeholder="Enter first number">
<input type="number" id="number2" value="9" placeholder="Enter second number">
<button id="greatButton">Find Greatest Number</button>
<script>
    var numberWorker = new Worker("numberWorker.js"),
        resultContainer = document.getElementById("resultContainer"),
        greatButton = document.getElementById("greatButton"),
            number1 = document.getElementById("number1"),
            number2=document.getElementById("number2");
    greatButton.addEventListener("click",function(){
        numberWorker.postMessage({
            number1:parseInt(number1.value,10),
            number2: parseInt(number2.value,10)
        });
    });
    numberWorker.addEventListener("message",function(workerEvent){
        var responseData = workerEvent.data;
        resultContainer.innerText = "Greatest Number: "+responseData.result;
    });
</script>
</body>
</html>

self.addEventListener("message",function(event){
   var numberWorker = self.importScripts('greatest-number-script.js');
    var requestData = event.data,
        number1 = requestData.number1,
        number2 = requestData.number2,
        greatestNumber = findGreatestNumber(number1,number2);
    self.postMessage({result:greatestNumber});
});

var findGreatestNumber = function(number1,number2){
    return number1>number2 ? number1 : number2;
};