Strings are a sequence of zero or more characters written inside quotes used to represent text.

Strings may consist of letters, numbers, symbols, words, or sentences.

Strings are immutable, they cannot be changed.

Each character in a string has an index.

The first character will be index 0 the second character will be index 1 and so on.

There are two ways to access an individual character in a string.

charAt() method

const str1 = "abc"; string

str1.charAt(0); character at index 0 → "a"

str1.charAt(1); character at index 1 → "b"

str1.charAt(2); character at index 2 → "c"

str1.charAt(3); character at index 3 → "" index not found

Alternatively use at() or slice() methods

bracket notation []

const str2 = "abc"; string

str2[0]; character at index 0 → "a"

str2[1]; character at index 1 → "b"

str2[2]; character at index 2 → "c"

str2[3]; character at index 3 → undefined index not found

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Arrays are used to store multiple values in a single variable.

Each value is called an element, and each element has a numeric position in the array, known as its index.

Arrays are zero-indexed, meaning the first element is at index 0, the second at index 1, and so on.

Arrays can contain any data type, including numbers, strings, and objects.

const arr1 = [2, 4, 6]; array

arr1[0]; element at index 0 → 2

arr1[1]; element at index 1 → 4

arr1[2]; element at index 2 → 6

arr1[3]; element at index 3 → undefined index not found

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Reverse a string using ↴

split() method → splits a string into an array of substrings.

reverse() method → reverses the order of the elements in an array.

join() method → returns an array as a string.

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split() method splits a string into an array of substrings based on a specified separator (delimiter). The original string is unchanged.

const str3 = "Hello"; → string

str3.split(""); returns ↴

["H", "e", "l", "l", "o"] → array

const str4 = "hello world"; → string

str4.split(" "); returns ↴

["hello", "world"] → array

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reverse() method reverses the order of the elements in an array.

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join() method joins all elements of an array into a string based on a specified separator. The original array is unchanged.

("") separator → string is joined with no spaces between each character.

(" ") separator → string is joined with no spaces between each word.

const arr4 = ["Hello", "World"]; array

arr4.join(" "); returns ↴

"Hello World" → string

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Chaining these 3 built-in functions together ↴

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Initialize a variable to hold the string to be reversed.

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Define a function reverseString to reverse a string.

function reverseString(str) {}

The function takes a string as input str and returns a new string with the characters reversed.

return str str chained with methods ↴

Split str into an array of characters.

.split("")

Reverse the array of characters.

.reverse()

Join the reversed array back into a string without spaces.

.join("")

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Call the function with ↴

reverseString(string1);

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Reverse a string.

const string1 = "Hello World";

function reverseString(str) {

return str.split("").reverse().join("");

}

call function

reverseString(string1); returns ↴

"dlroW olleH"

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Alternatives to convert a string into an array of substrings ↴

const str6 = "Hello";

str6.split(""); returns ↴

["H", "e", "l", "l", "o"] → array

const str7 = "Hello";

[...str7]; returns ↴

["H", "e", "l", "l", "o"] → array

const str8 = "Hello";

Array.from(str8); returns ↴

["H", "e", "l", "l", "o"] → array