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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Numbers are used to represent both integer and floating-point values.

Numbers are most commonly expressed in literal forms like 255 or 3.14159 ↴

let num1 = 5; → number

let num2 = 2.5; → number

let num3 = num1 + num2;

console.log(num3); returns ↴

7.5 → number

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Convert string to title case using ↴

for loop → executes a block of code a number of times.

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

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

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

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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for loop repeatedly executes a block of code until a specified condition evaluates to false.

The loop runs a block of code a set number of times, defined by an initialization, a condition, and an increment.

for (let x = 0; x < 4; x++) {

console.log(x);

}

Loop variable x is initialized to 0

Condition x < 4 is checked before each iteration.

The loop will continue to run as long as x is less than 4

The loop repeatedly executes a block of code 4 times, from 0 to 3

For each iteration of the loop, the current value of x is printed to the console.

After each iteration, x is incremented by 1 x++

When x reaches 4 the condition evaluates to false, terminating the loop.

0

1

2

3 → printed to console

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

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

const str5 = "hello";

str5.charAt(0); → "h" first character

str5.charAt(1); → "e"

str5.charAt(2); → "l"

str5.charAt(3); → "l"

str5.charAt(4); → "o"

str5.charAt(5); → "" not found

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

syntax ↴

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

slice(start, end) return an array from start index to end index of array (exclusive).

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

const arr2 = [1, 2, 3, 4];

arr2.slice(1); start index is 1

returns ↴

[2, 3, 4]

Return a new array from index 1 to index 4 (exclusive).

const arr3 = [1, 2, 3, 4];

arr3.slice(1, 3); start index is 1 end index is 4 (not included)

returns ↴

[2, 3]

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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 arr5 = ["Hello", "World"]; array

arr5.join(" "); returns ↴

"Hello World" → string

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

const str6 = "hELlo wORLd";

str6.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 str7 = "hELlo wORLd";

str7.toUpperCase(); returns ↴

"HELLO WORLD" → uppercase

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Initialize a variable to hold the string to tranform to title case.

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Define a function toTitleCase to tranform a string into title case.

function toTitleCase(str) {}

The function takes a string as input str and returns a new string that is transformed into title case. The original string remains unchanged.

Convert the entire string to lower case and split the string into an array of words.

str = str.toLowerCase().split(" ")

Iterate through each word in the array.

for (let x = 0; x < str.length; x++)

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

return str.join(" ")

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Call the function with ↴

toTitleCase(string1);

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Convert string to title case.

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Alternative to remove one or more spaces from string ↴

Use trim() method to remove spaces from both ends of the string.

Use a regular expression as the separator to split the string into an array of words using one or more spaces.