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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Extract initials from a string using ↴

Regular Expression → patterns used to match character combinations in strings.

match → method retrieves the result of matching a string against a regular expression.

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

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

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Regular expressions are patterns used to match character combinations in strings.

The regular expression /\b\w/g is used to match the first character of each word.

It matches the position between a word character (like letters and digits) and a non-word character (like spaces or punctuation).

Replace the first character of each word with an underscore character "_"

const str3 = "jack of all trades";

str3.replace(/\b\w/g, "_") returns ↴

"_ack _f _ll _rades" first letter of each word replaced with an underscore

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match() method returns an array of the first occurrence of any match found. If no match is found, it returns null.

Find all capital letters in the string.

const str4 = "Hello World"; → string

str4.match(/[A-Z]/g); returns ↴

["H", "W"] → 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 arr3 = ["Hello", "World"]; array

arr3.join(" "); returns ↴

"Hello World" → string

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

const str5 = "hELlo wORLd";

str5.toUpperCase(); returns ↴

"HELLO WORLD" → uppercase

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Ternary Operator

Ternary Operator is frequently used as an alternative to if...else statements.

if (condition) {

expressionIfTrue;

} else {

expressionIfFalse;

}

Ternary Operator takes three operands ↴

condition evaluates to true or false.

? question mark → expression to execute if the condition is truthy

: colon → expression to execute if the condition is falsy

condition ? expressionIfTrue : expressionIfFalse

let score = 75;

let result = score >= 55

? "You passed"

: "You failed";

console.log(result); returns ↴

You passed → first expression executed

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Initialize a variable to hold the string to extract initials

const string1 = "Fear of missing out"; → user input

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Define a function getInitials to extract initials from a string.

function getInitials(str) {}

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

match() method returns an array of all matches found in the string.

Use a regular expression to match the first letter of each word.

If initials are found, a ternary operator joins them into a single string without spaces, and converts them to upper case.

initials.join("").toUpperCase()

If no initials are found, it returns an empty string ""

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Call the function with ↴

getInitials(string1);

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Extract initials from a string.