CSS

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]

array map

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]

array map

let numbers = [1, 2, 3, 4]
let filteredNumbers = numbers.map(function(_, index) {
  if (index < 3) {
     return num
  }
})
// index goes from 0, so the filterNumbers are 1,2,3 and undefined.
// filteredNumbers is [1, 2, 3, undefined]
// numbers is still [1, 2, 3, 4]

array.map

let arr = [1,2,3]

/*
  map accepts a callback function, and each value of arr is passed to the 
  callback function. You define the callback function as you would a regular
  function, you're just doing it inside the map function
  
  map applies the code in the callback function to each value of arr, 
  and creates a new array based on your callback functions return values
*/
let mappedArr = arr.map(function(value){
	return value + 1
})

// mappedArr is:
> [2,3,4]

array.map

var x = [1,2,3,4].map( function(item) {return item * 10;});

array 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 ͡°)

array map

let numbers = [1, 2, 3, 4]
let filteredNumbers = numbers.map(function(num, index) {
  if (index < 3) {
     return num
  }
})
// index goes from 0, so the filterNumbers are 1,2,3 and undefined.
// filteredNumbers is [1, 2, 3, undefined]
// numbers is still [1, 2, 3, 4]

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

Array.map method

const shoppingList = ['Oranges', 'Cassava', 'Garri', 'Ewa', 'Dodo', 'Books']

export default function List() {
  return (
    <>
      {shoppingList.map((item, index) => {
        return (
          <ol>
            <li key={index}>{item}</li>
          </ol>
        )
      })}
    </>
  )
}