Array Methods

Arrays are versatile for storing and retrieving data. Retrieving data using square brackets [] is called indexing.

However, there are various methods available for working with arrays.

Adding Elements

There are different ways to add elements to an array.

Push

The push() method adds a new value to the end of the array:


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let arr = [1, 2, 3];

arr.push(4);
arr.push(5);
arr.push(6);

console.log(arr);

Unshift

The unshift() method works like the push() method, but it inserts the value at the beginning of the array.


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let arr = [1, 2, 3];
console.log("Array:", arr);

arr.unshift(222);  // Insert element at the start

console.log("Array:", arr);

Indexing

You can append a new value by indexing:


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let arr = [1, 2];

arr[2] = 3;
arr[3] = 4;

console.log(arr);

Indexing allows you to assign a value to a specified index, reassign a previous value, and more:


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let arr = [1, 2, 3];

arr[0] = 4;

console.log("Array:", arr);

To create a new element in the array without mistakes, you can use the push(value) method or the arr[arr.length] = value expression:


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let myArray = [];

myArray[myArray.length] = "indexing";
console.log("After first indexing:", myArray);

myArray.push("pushing");
console.log("After first pushing:", myArray);

myArray[myArray.length] = "indexing";
console.log("After second indexing:", myArray);

myArray.push("pushing");
console.log("After second pushing:", myArray);

Deleting Elements

Sometimes, you may need to delete elements from an array. This can be done in different ways.

Pop

The pop() method deletes the last element in an array and allows you to save it to another variable:


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let arr = [11, 22, 33, 44];
console.log("Array:", arr);

let x = arr.pop(); // Remove and save the last element in `arr` to variable `x`

console.log("Popped element:", x);
console.log("Array now:", arr);

Shift

The shift() method works like pop(), but it removes the first element from an array:


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let arr = [11, 22, 33, 44, 55, 66];
console.log("Array:", arr);

let popped = arr.pop();  // Remove the last element

console.log("Popped:", popped);
console.log("Array:", arr);

let shifted = arr.shift();  // Remove the first element

console.log("Shifted:", shifted);
console.log("Array:", arr);

1. How can we add an element to the end of the array?

2. How can we remove the last element in the array?

Tudo estava claro?

Obrigado pelo seu feedback!

Seção 2. Capítulo 7