JAVASCRIPT

How does map works in javascript?

const products = [
    { name: 'Laptop', price: 32000, brand: 'Lenovo', color: 'Silver' },
    { name: 'Phone', price: 700, brand: 'Iphone', color: 'Golden' },
    { name: 'Watch', price: 3000, brand: 'Casio', color: 'Yellow' },
    { name: 'Aunglass', price: 300, brand: 'Ribon', color: 'Blue' },
    { name: 'Camera', price: 9000, brand: 'Lenovo', color: 'Gray' },
];

const productName = products.map(product => product.name);
console.log(productName);
//Expected output:[ 'Laptop', 'Phone', 'Watch', 'Aunglass', 'Camera' ]

array map javascript

const array1 = [1, 4, 9, 16];

// pass a function to map
const map1 = array1.map(x => x * 2);

console.log(map1);
// expected output: Array [2, 8, 18, 32]

javascript map

array.map((item) => {
  return item * 2
} // an example that will map through a a list of items and return a new array with the item multiplied by 2

javascript map

const items = [1, 2, 3, 4, 5, 6, 7, 8, 9];

const anotherItems = items.map(item => item * 2);

console.log(anotherItems);

javascript map function

/* Answer to: "javascript map function" */

/*
  <Array>.map() - One of the most useful in-built methods in JavaScript (imo).

  The map() method creates a new array populated with the results of calling
  a provided function on every element in the calling array.
 
  For more information, click on the source link.

  Let me make some examples of it's uses:
*/

let array = [1, 4, 9, 16];
array.map(num => num * 2); // [2, 8, 18, 32];
array.map(pounds => `£${pounds}.00`); // ["£1.00", "£4.00", "£9.00", "£16.00"];
array.map(item => Math.sqrt(item)); // [1, 2, 3, 4];

how to use the map method in javascript

const numbers = [1, 2, 3, 4, 5]; 

const bigNumbers = numbers.map(number => {
  return number * 10;
});

how the map function works javascript

const array = [2, 5, 9];
let squares = array.map((num) => num * num);

console.log(array); // [2, 5, 9]
console.log(squares); // [4, 25, 81]

javascript map

const numbers = [0,1,2,3];

console.log(numbers.map((number) => {
  return number;
}));

javascript map

// make new array from edited items of another array
var newArray = unchangedArray.map(function(item, index){
  return item;	// do something to returned item
});

// same in ES6 style (IE not supported)
var newArray2 = unchangedArray.map((item, index) => item);

JavaScript Array Methods .map()

let numbers = [1, 2, 3, 4, 5];
let doubles = numbers.map(number => number * 2)
console.log(doubles)
// --> [ 2, 4, 6, 8, 10 ]

javascript map

const numbers = [2, 4, 6, 8];
const result = numbers.map(a => a * 2);
console.log(result);
//Output: [ 4, 8, 12, 16 ]

JavaScript Array map()

const numbers1 = [45, 4, 9, 16, 25];
const numbers2 = numbers1.map(myFunction);

function myFunction(value, index, array) {
  return value * 2;
}

map function in js

var array = "M 175 0 L 326.55444566227675 87.50000000000001 L 326.55444566227675 262.5 L 175 350 L 23.445554337723223 262.5 L 23.44555433772325 87.49999999999999 L 175 0".split(" ");

let neWd = array.map(x => {
	if (x === 'M' || x === 'L'){
		return x;
	}else{
		return x * 2;
	}
}).join(' ')

console.log(neWd);

javascript map

// Creating javascript map with one instruction
const map = new Map([
  ["key", "value"],
  ["key2", "value2"],
]);

JavaScript map

function square(arr) {
       const newArr = arr.map(x => x * x );
    return newArr ;
  
  //if you find this answer is useful ,
//upvote ⇑⇑ , so can the others benefit also . @mohammad alshraideh ( ͡~ ͜ʖ ͡°)

JavaScript Map Function

const myAwesomeArray = [5, 4, 3, 2, 1]

myAwesomeArray.map(x => x * x)

// >>>>>>>>>>>>>>>>> Output: [25, 16, 9, 4, 1]

javaScript Map() Method

// Create a Map
const fruits = new Map([
  ["apples", 500],
  ["bananas", 300],
  ["oranges", 200]
]);

javascript map

Shorthand: (key,value) Map 

const callbackMap = new Map<string, PushEventCallback>([
      ["addComment", addCommentCallback],
      ["commentModified", editCommentCallback]
]);

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map#:~:text=Cloning%20and%20merging%20Maps

js map()

var number = [1, 2 , 3, 4, 5, 6, 7, 8, 9]; 
var doubles  = number.map((n) => { return n*2 })

/*  doubles 
    (9) [2, 4, 6, 8, 10, 12, 14, 16, 18] */

javascript map

const originals = [1, 2, 3];

const doubled = originals.map(item => item * 2);

console.log(doubled); // [2, 4, 6]

map function

# map function
city_lengths = map(len, ['sanjose', 'cupertino', 'sunnyvale', 'fremont'])
print(list(city_lengths))

# [7, 9, 9, 7]
# Map takes a function and a collection of items. It makes a new, empty collection, runs the function on each item in the original collection and inserts each return value into the new collection. It returns the new collection.

map function javascript

var rebels = pilots.filter(function (pilot) {  return pilot.faction === "Rebels";});var empire = pilots.filter(function (pilot) {  return pilot.faction === "Empire";});

map function

const ratings = watchList.map(item => ({
  title: item["Title"],
  rating: item["imdbRating"]
}));

map method in javascript

const colorData = ['red','blue','green']
const result = colorData.map((el)=>el)
console.log(result)

javascript array map

const array = [1, 4, 9, 16];

const arrayWithMultipliedElems = array.map(elem => elem * 2);

console.log(arrayWithMultipliedElems); // [2, 8, 18, 32]

function with .map javascript

const numbers = [2, 7, 9, 171, 52, 33, 14]
const toSquare = num => num * num

const squareNums = newNumbers => 
  newNumbers.map(toSquare);

console.log(squareNums(numbers));

js array map

let A = [9000, 8500, 5500, 6500];
let B = A.map(function (value, index, array) {
    return value*2; // forEach 沒有在 return 的，所以不會有作用
});
console.log(B); // undefined