Introduction

JavaScript arrays provide several built-in methods to manipulate and process data easily. These methods help developers write cleaner and more readable code compared to traditional loops.

This assignment explains the following array methods:

• push() and pop()

• shift() and unshift()

• map()

• filter()

• reduce()

• forEach()

Each method is explained with a simple practical example and the before and after array state.

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1. push() and pop()

push()

push() adds a new element at the end of an array.

let numbers = [1, 2, 3];

numbers.push(4);

console.log(numbers);

Before

[1, 2, 3]

After

[1, 2, 3, 4]

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pop()

pop() removes the last element from an array.

let numbers = [1, 2, 3];

numbers.pop();

console.log(numbers);

Before

[1, 2, 3]

After

[1, 2]

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2. shift() and unshift()

shift()

shift() removes the first element of an array.

let numbers = [10, 20, 30];

numbers.shift();

console.log(numbers);

Before

[10, 20, 30]

After

[20, 30]

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unshift()

unshift() adds a new element at the beginning of the array.

let numbers = [20, 30];

numbers.unshift(10);

console.log(numbers);

Before

[20, 30]

After

[10, 20, 30]

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3. map()

map() creates a new array by transforming each element.

Example: Double each number

let numbers = [2, 4, 6];

let doubled = numbers.map(function(num) {
  return num * 2;
});

console.log(doubled);

Before

[2, 4, 6]

After

[4, 8, 12]

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4. filter()

filter() creates a new array with elements that satisfy a condition.

Example: Numbers greater than 10

let numbers = [5, 12, 8, 20];

let result = numbers.filter(function(num) {
  return num > 10;
});

console.log(result);

Before

[5, 12, 8, 20]

After

[12, 20]

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5. reduce()

reduce() is used to combine all elements into a single value such as a total sum.

Example: Find total sum

let numbers = [5, 10, 15];

let sum = numbers.reduce(function(total, num) {
  return total + num;
}, 0);

console.log(sum);

Result

30

Here:

• total stores accumulated value

• num is the current element

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6. forEach()

forEach() runs a function for every element in the array.

let numbers = [1, 2, 3];

numbers.forEach(function(num) {
  console.log(num);
});

Output

1
2
3

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