Arrays

• Arrays are variables that can hold more than one value.
• The values may also be of different types.

Example

const number = [1, 2, 3, 4];

const names = ["Jonh", "Tom", "Harry"];

const bool = [true, false];

const mixed = [1, "Ron", true, null, undefined];

console.log ("Number-array:", number);
console.log ("Names-array:", names);
console.log ("Bool-array:", bool);
console.log ("Mixed-array:", mixed);

Output

Getting access to Array Elements

• You can access array elements using index.
• Index start from 0.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("At index 0:", names[0]);
console.log ("At index 1:", names[1]);
console.log ("At index 2:", names[2]);

Output

Change the value of array element.

• You need to access the array element using index and assign new value to it.

Example

const names = ["Jonh", "Tom", "Harry"];
names[0] = "Ron"


console.log ("At index 0:", names[0]);

Output

The length property

• .length property returns the length of array.
• It always returns one more than the highest index of array.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Length of names array: ", names.length);

Output

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Arrays Methods

• The built-in array attributes and methods are the true power of JavaScript arrays.

toString()

• It converts array to a string and all the value will be seperated with comma.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Length of names array: ", names.toString());

Output

join()

• It also acts like toString() but you can specify your seperator in this case.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Length of names array: ", names.join("-"));

Output

pop()

• Removes the last element from the array and returns it.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using pop on array: ", names.pop());
console.log ("After array: ", names);

Output

push()

• Adds a new element at the end of the array and returns length of the array.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using push on array: ", names.push("Ron"));
console.log ("After array: ", names);

Output

shift()

• Removes the first element and returns it.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using shift on array: ", names.shift());
console.log ("After array: ", names);

Output

unshift()

• Adds element to the beginning and return length of the array.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using unshift on array: ", names.unshift("Ron"));
console.log ("After array: ", names);

Output

concat()

• It joins array to the given array.
• Note - It returns new array, It does not change the original array

Example

const names = ["Jonh", "Tom", "Harry"];
const number = [1, 2, 3, 4];

console.log ("Before array: ", names);
console.log ("Using concat on array: ", names.concat(number));

Output

sort()

• It sorts array alphabetically.
• Note - It modifies the original array

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using sort on array: ", names.sort());

Output

splice()

• It can be use to add elements to a specific place and can remove some elements.

Example

const names = ["Jonh", "Tom", "Harry"];

console.log ("Before array: ", names);
console.log ("Using splice on array: ", names.splice(1, 2, "Jerry", "Ron"));
console.log ("Before array: ", names);

Output

Description

slice()

• It slices out a peice of an array.
• Note - It creates a new array and returns it

Example

const number = [1, 2, 3, 4, 5];

console.log ("Before array: ", number);
console.log ("Using slice on array: ", number.slice(4));
console.log ("Using slice on array: ", number.slice(1, 3));

Output

Description

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And that's all from my side

I hope this reference guide has been helpful for you.