Dates in JavaScript take milliseconds since epoch. If the epoch in milliseconds is 1514789449605, then let us convert it into a meaningful JavaScript date.
Example
<html>
<head>
<title>JavaScript Dates</title>
</head>
<body>
<script>
var val ="/Date(1514789449605)/";
var myDate = new Date( parseFloat( val.substr(6 )));
document.write("Converted Date:"+ (myDate.getMonth() + 1) + "/" +
myDate.getDate() + "/" + myDate.getFullYear() + " " +
myDate.getHours() + ":" + myDate.getMinutes() + ":" +
myDate.getSeconds()
);
</script>
</body>
</html>Output
Converted Date:1/1/2018 12:20:49