what is array map() in JavaScript

map() method creates a new array with the results of calling a function for every array element.

A function that is executed for every element in the array is passed into map() which has these parameters:

• current element
• the index of the current element
• array that map() is being called on

An example of using map() would be to square every element in an array

let numbers = [2, 4, 6, 8, 10]; // function to return the square of a number function square(number) { return number * number; } // apply square() function to each item of the numbers list let square_numbers = numbers.map(square); console.log(square_numbers); // Output: [ 4, 16, 36, 64, 100 ] 

Another example is converting an array of data into JSX.

const food = [ { id: 0, name: 'orange', color: 'orange' }, { id: 1, name: 'banana', color: 'yellow' } ]; food.map(food => { return ( <div key={food.id}> <div> {food.name} - {food.color} </div>  </div>  ); }); 

summary of map()

Use map() when something needs to be done on every element in an array.