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| Object Assign |
Object Assign
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The Object.assign() method is used to 1) add properties and values to an existing object, 2) make a new copy of an existing object, or 3) combine multiple existing objects into a single object. The Object.assign() method requires one targetObject as a parameter and can accept an unlimited number of sourceObjects as additional parameters.
Important to note here is that the targetObject parameter will always be modified. If that parameter points to an existing object, then that object will be both modified and copied. If, however, you wish to create a copy of an object without modifying that original object, you can pass an empty object {} as the first (or targetObject) parameter and the object to be copied as the second (or sourceObject) parameter.
If objects passed as parameters into Object.assign() share the same properties (or keys), property values that come later in the parameters list will overwrite those which came earlier.
Syntax
Object.assign(targetObject, ...sourceObject)
Return Value
Object.assign() returns the targetObject.
Examples
Modifying and Copying targetObject
let obj = {name: 'Dave', age: 30};
let objCopy = Object.assign(obj, {coder: true});
console.log(obj); // returns { name: 'Dave', age: 30, coder: true }
console.log(objCopy); // returns { name: 'Dave', age: 30, coder: true }
Copying targetObject Without Modification
let obj = {name: 'Dave', age: 30};
let objCopy = Object.assign({}, obj, {coder: true});
console.log(obj); // returns { name: 'Dave', age: 30 }
console.log(objCopy); // returns { name: 'Dave', age: 30, coder: true }
Objects With Same Properties
let obj = {name: 'Dave', age: 30, favoriteColor: 'blue'};
let objCopy = Object.assign({}, obj, {coder: true, favoriteColor: 'red'});
console.log(obj); // returns { name: 'Dave', age: 30, favoriteColor: 'blue' }
console.log(objCopy); // { name: 'Dave', age: 30, favoriteColor: 'red', coder: true }