var run = document.getElementById("run");
var open = document.getElementById("open");
run.addEventListener("click", function() {
var end = Date.now() + 2000;
console.log("Running: getUser(1)");
while(Date.now() < end) {}
end = Date.now() + 2000;
console.log("Running: getUser(2)");
while(Date.now() < end) {}
end = Date.now() + 2000;
console.log("Running: getUser(3)");
while(Date.now() < end) {}
alert("Finish");
});
open.addEventListener("click", function() {
alert("Helo");
});
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</head>
<body>
<p>var foo = getUser(1);</p>
<p>var bar = getUser(2);</p>
<p>var baz = getUser(3);</p>
<button id="run">Run</button>
<button id="open">Open</button>
</body>
</html>