map

Describing the map Operation

  • The map operation is used for applying a function to each element of an array;

  • It accepts a callback function with the following arguments:

    • currentValue: Current element processed in the array
    • index: Optional index of currentValue
    • array: Optional array that is called
    • thisArg: Optional value to use as this

Defining an Array

let fruits = ["Apple", "Banana"];
console.log(fruits.length);
// 2

Using the map Operation

// Regular function
let f = fruits.map(function(item, index, array) {
    return item + " Pie";
})
console.log(f);
// ["Apple Pie", "Banana Pie"]

// Arrow function
let f = fruits.map(item => item + " Pie");
console.log(f);
// ["Apple Pie", "Banana Pie"]

// forEach
let f = fruits.forEach(item => item + " Pie");
console.log(f);
// undefined
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