Here we are considering only shallow copy of objects. We are not considering deep cloning of objects. Following are the common ways of cloning object in JavaScript:

1. Object.assign() method

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

const source = {key1:1, key2:'Hello World'}
const const target={};
const clone = Object.assign(target, source);
console.log(source);
console.log(target);
console.log(clone);

Output

{key1: 1, key2: "Hello World"}
{key1: 1, key2: "Hello World"}
{key1: 1, key2: "Hello World"}

2. Spread Operator

It adds spread properties to object literals. It copies own enumerable properties from a provided object onto a new object. Note that Object.assign() triggers setters whereas spread syntax doesn’t.

var obj1 = {key1:1, key2:'Hello World'};
var clone = {...obj1};
console.log(clone);

Output

{key1: 1, key2: "Hello World"}

3. JSON stringify/parse

let clone = JSON.parse(JSON.stringify(objectToClone));

Note that JSON method will loose any Javascript types that have no equivalent in JSON. For example:

JSON.parse(JSON.stringify({a:null,b:NaN,c:Infinity,d:undefined,e:function(){},f:Number,g:false})) will generate {a: null, b: null, c: null, g: false}

Example:

var clone = JSON.parse(JSON.stringify({key1:1, key2: 'Hello World'}));
console.log(clone);

Output

{key1: 1, key2: "Hello World"}

4. Manually iterating properties of objects

You can write a function to iterate properties of an object and create a clone manually. Following is a basic function to create a function using this approach:

function fun(obj) {
    let cloneObject = {};
    for (let prop in obj) {
        if (obj.hasOwnProperty(prop)) {
            cloneObject[prop] = obj[prop];
        }
    }
    return cloneObject;
}