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
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
Capitalize Nth character of a string using ↴
slice() method → extracts a part of a string and returns it as a new string, without modifying the original 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.
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 str1 = "Hello World";
str1.slice(1); start index is 1
returns ↴
"ello World"
Return a new string from index 1 to index 9 (exclusive).
const str2 = "Hello World";
str2.slice(1, 9); start index is 1 end index is 9 (not included)
returns ↴
"ello Wor"
toLowerCase() method converts all letters to lower case. The original string is unchanged.
const str3 = "hELlo wORLd";
str3.toLowerCase(); returns ↴
"hello world" → lower case
toUpperCase() method converts all letters to upper case. The original string is unchanged.
const str4 = "hELlo wORLd";
str4.toUpperCase(); returns ↴
"HELLO WORLD" → upper case
Initialize a variable to hold the string to capitalize the Nth character.
const string1 = "Hello World"; → user input
Initialize a variable to hold the Nth position.
const num1 = 5; → user input
Define a function capitalizeNthChar to capitalize the Nth character of a string.
function capitalizeNthChar(str, num) {}
The function takes a string and number as input str, num and returns a new string with the Nth character of string capitalized. The original string remains unchanged.
Check if the provided number is within the valid range, between 1 and string length.
if (num > 0 && num <= str.length) {}
Convert the string to lower case.
let lowerStr = str.toLowerCase() lowerStr
Strings are zero-indexed, meaning the first character is at index 0, the second at index 1, and so on.
num is the Nth character to find.
Index of position 1 will be num - 1 1 - 1 [0]
Index of position 2 will be num - 1 2 - 1 [1]
Index of position 3 will be num - 1 3 - 1 [2]
and so on ...
Get the Nth character and convert it to upper case.
const nthChar = lowerStr[num - 1].toUpperCase() nthChar
Return the modified string with the Nth character capitalized.
return lowerStr.slice(0, num - 1) + nthChar + lowerStr.slice(num)
slice(0, num - 1) string from index 0 to Nth character (exclusive).
nthChar Nth character to capitalize.
slice(num) string from num to end of string.
Call the function with ↴
capitalizeNthChar(string1, num1);
Capitalize 5th character in string.
const string1 = "hello world";
const num1 = 5;
function capitalizeNthChar(str, num) {
if (num > 0 && num <= str.length) {
let lowerStr = str.toLowerCase();
const nthChar = lowerStr[num - 1].toUpperCase();
return lowerStr.slice(0, num - 1) + nthChar + lowerStr.slice(num);
}
}
call function
capitalizeNthChar(string1, num1); returns ↴
"hellO world" 5th character capitalized