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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Capitalize first character of each word using ↴

map() method → creates a new array from calling a function for every array element.

charAt() method → returns the character at a specified index in a string.

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

slice() method → returns selected elements in an array, as a new array.

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

toLowerCase() method → returns the value of the string converted to lower case.

toUpperCase() method → returns the value of the string converted to upper case.

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map() method creates a new array populated with the results of calling a provided function on every element in the calling array. The original array is unchanged.

const arr2 = [5, 10, 15, 20];

arr2.map((x) => x + 10); returns ↴

[15, 20, 25, 30] → 10 added to each element

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toLowerCase() method returns a new string with all letters converted to lower case. The original string is unchanged.

const str3 = "hELlo wORLd";

str3.toLowerCase(); returns ↴

"hello world" → lower case

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toUpperCase() method returns a new string with all letters converted to upper case. The original string is unchanged.

const str4 = "hELlo wORLd";

str4.toUpperCase(); returns ↴

"HELLO WORLD" → upper case

toUpperCase() method can be used to capitalize a single letter.

const str5 = "h"; lower case

str5.toUpperCase(); returns ↴

"H" → upper case

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charAt() method returns the character at the given index.

If the index is out of range an empty string "" is returned.

const str6 = "hello";

str6.charAt(0); → "h" first character

str6.charAt(1); → "e"

str6.charAt(2); → "l"

str6.charAt(3); → "l"

str6.charAt(4); → "o"

str6.charAt(5); → "" not found

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slice() method extracts a part of a string and returns it as a new string, without modifying the original string.

syntax ↴

slice(start) return a new string from start index to end of string

slice(start, end) return a string from start index to end index of string (exclusive).

Return a new string from index 1 to end of string.

const str7 = "Hello World";

str7.slice(1); start index is 1

returns ↴

"ello World"

Return a new string from index 1 to index 9 (exclusive).

const str8 = "Hello World";

str8.slice(1, 9); start index is 1 end index is 9 (not included)

returns ↴

"ello Wor"

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The capitalized first character can then be concatenated with the rest of the string.

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To capitalize each word in a string we can divide the string into an array of words.

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

const str10 = "Hello"; → string

str10.split(""); returns ↴

["H", "e", "l", "l", "o"] → array

const str11 = "hello world"; → string

str11.split(" "); returns ↴

["hello", "world"] → array

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join() method joins all elements of an array into a single string with a specified separator between each element. The original array is unchanged.

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

arr4.join(" "); returns ↴

"Hello World" → string

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Initialize a variable to hold the string to capitalize first letter of each word.

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Define a function capWords to capitalize first letter of each word.

function capWords(str) {}

The function takes a string as input str and returns a new string with the first letter of each word capitalized. The original string remains unchanged.

Convert str to lower case.

return str.toLowerCase()

Split str into an array of words.

.split(" ")

map() method creates a new array by applying a callback function to each element of the array.

map(calbackFn) ↴

Join the array back into a single string with spaces in between.

.join(" ")

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Call the function with ↴

capWords(string1);

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Capitalize first letter of each word.

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Capitalize first letter of each word.

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Alternatives to access an individual character in a string ↴

const myStr = "ABCDE";

myStr.at(2); → "C"

myStr.charAt(2); → "C"

myStr.slice(2, 3); → "C"

myStr.substring(2, 3); → "C"

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Alternatives ↴