Javascript map values to array code example

Example 1: javascript map array

const myArray = ['Sam', 'Alice', 'Nick', 'Matt'];

// Appends text to each element of the array
const newArray = myArray.map(name => {
	return 'My name is ' + name; 
});
console.log(newArray); // ['My name is Sam', 'My Name is Alice', ...]

// Appends the index of each element with it's value
const anotherArray = myArray.map((value, index) => index + ": " + value);
console.log(anotherArray); // ['0: Sam', '1: Alice', '2: Nick', ...]

// Starting array is unchanged
console.log(myArray); // ['Sam', 'Alice', 'Nick', 'Matt']

Example 2: node get value from map

let myMap = new Map();

myMap.set("key1", "value1");
myMap.set("key2", "value2");

console.log(myMap.has("key1")); // true
console.log(myMap.has("key2")); // true

console.log(myMap.get("key1")); // value1
console.log(myMap.get("key2")); // value2

// NOTE: DO NOT try to access map values using [].
// myMap["key1"] = "value1";

Example 3: javascript map array

const sweetArray = [2, 3, 4, 5, 35]
const sweeterArray = sweetArray.map(sweetItem => {
    return sweetItem * 2
})

console.log(sweeterArray)

Example 4: map a keys from an array in a separate arraylist javascript

const myUsers = [
    { name: 'shark', likes: 'ocean' },
    { name: 'turtle', likes: 'pond' },
    { name: 'otter', likes: 'fish biscuits' }
]

const usersByLikes = myUsers.map(item => {
    const container = {};

    container[item.name] = item.likes;
    container.age = item.name.length * 10;

    return container;
})

console.log(usersByLikes);