Underscore.js, a library of javascript, has introduced a method called _.extend() to shallow copy the objects in javascript. This method copy all of the properties in the source objects over to the destination object, and return the destination object. Here the reference is used to copy but not the duplication.
syntax
_.extend(object*);
It accepts objects and shallow copy them. We can provide as many objects as we can.
Example-1
In the following example, three individual objects were copied shallowly and executed in the output.
<html>
<body>
<script
src="//cdnjs.cloudflare.com/ajax/libs/lodash.js/0.10.0/lodash.min.js"></script>
</head>
<body>
<script>
var res = JSON.stringify(_.extend(
{name: 'Ram', designation: "content developer"},
{age: 50},
{salary: 1200000}));
document.write((res));
</script>
</body>
</html>Output
{"name":"Ram","designation":"content developer","age":50,"salary":1200000}Example-2
<html>
<body>
<script
src="//cdnjs.cloudflare.com/ajax/libs/lodash.js/0.10.0/lodash.min.js"></script>
</head>
<body>
<script>
var res = JSON.stringify(_.extend(
{name: 'Ram', designation: "content developer"},
{age: 50,salary: 1200000},
{country: "India"}));
document.write((res));
</script>
</body>
</html>Output
{"name":"Ram","designation":"content developer","age":50,"salary":1200000,"country":"India"}