How to use the map() method In Javascript
The Array.map() method of JavaScript can be used to iterate through each element of the array and then the set() method of JavaScript map can be used to set the properties of the JavaScript map.
Syntax:
arrayName.map((item)=>{ mapName.set()});
Example: The below example is the practical implementation of the map() method to convert an array of objects to a map.
const objectsArray =
[
{
type: "Company",
name: "w3wiki"
},
{
type: "Cricketer",
name: "Virat Kohli"
}
];
console.log("Array of objects is: ", objectsArray);
const createdMap = new Map();
objectsArray.map((obj) => {
createdMap.set(obj.type, obj.name);
});
console.log("Created Map: ", createdMap);
Output
Array of objects is: [ { type: 'Company', name: 'w3wiki' }, { type: 'Cricketer', name: 'Virat Kohli' } ] Created Map: Map(2) { 'Company' => 'w3wiki', 'Cricketer' => 'Virat Kohli' }...
How to Convert an Array of Objects to a Map in JavaScript ?
An array of objects can contain multiple objects with the same properties i.e. key-value pairs. But a map does not contain duplicate values which means if you convert an array of objects with duplicate objects into a map, it will contain only the unique key-value pairs.
Example:
Input Array:
[
{ type: 'Company', name: 'w3wiki' },
{ type: 'Cricketer', name: 'Virat Kohli' },
{ type: 'Cricketer', name: 'Virat Kohli' }
]
Output Map: Map(2)
{
'Company' => 'w3wiki',
'Cricketer' => 'Virat Kohli'
}
The below approaches can be used to convert an array of objects to a map in JavaScript:
Table of Content
- Using the map() method
- Using the reduce() method
- Using the forEach() method
- Using the Object.enteries() method
- Using the for-of loop
- Using the findIndex() Method