map javascrit 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: map javascript

function each(collection, action) {
  if (Array.isArray(collection)) {
    for (var i = 0; i < collection.length; i++) {
      action(collection[i], i, collection);
    }
  } else {
    for (var key in collection) {
      action(collection[key], key, collection);
    }
  }
}

Example 3: javascript map

// The map() method creates a new array populated with the 
// results of calling a provided function on every element
// in the calling array.
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]