Javascript String Manipulation

Concat

The concat method is used to join two or more strings together. This method does not change the existing strings, but returns a new string containing the text of the joined strings.

let str1 = "Hello, ";
let str2 = "World!";
let result = str1.concat(str2);

console.log(result); // Outputs: "Hello, World!"

str1 and str2 are two strings. The concat method is called on str1 with str2 as the argument, resulting in a new string that is the concatenation of str1 and str2. The new string is stored in the result variable.

CharAt

charAt method is used to get the character at a specific index in a string. The index of the first character is 0, the second character is 1, and so on.

let str = "Hello, World!";
let char = str.charAt(7);

console.log(char); // Outputs: "W"

Here, str is a string. The charAt method is called on str with 7 as the argument, which corresponds to the 8th character in the string (since the index is 0-based). The character at this index is “W”, so “W” is stored in the char variable and then logged to the console.

Includes

The includes method is used to determine whether one string can be found within another string, returning true or false as appropriate. It performs a case-sensitive search.

let str = "Hello, World!";
let result = str.includes("World");

console.log(result); // Outputs: true

str is a string. The includes method is called on str with “World” as the argument. Since “World” is a substring of str, the includes method returns true, which is stored in the result variable and then logged to the console.

IndexOf

indexOf method is used to determine the first occurrence of a specified value in a string. It returns the index of the value if found, or -1 if the value is not found. The search is case-sensitive.

let str = "Hello, World!";
let index = str.indexOf("World");

console.log(index); // Outputs: 7

str is a string. The indexOf method is called on str with “World” as the argument. Since “World” is a substring of str and starts at index 7, the indexOf method returns 7, which is stored in the index variable and then logged to the console.

Slice

The slice method is used to extract a section of a string and returns it as a new string, without modifying the original string. The method takes two parameters: the start index (inclusive), and the end index (exclusive).

let str = "Hello, World!";
let slicedStr = str.slice(7, 12);

console.log(slicedStr); // Outputs: "World"

Here, str is a string. The slice method is called on str with 7 as the start index and 12 as the end index. This extracts the substring starting from the 8th character up to (but not including) the 13th character. The resulting substring “World” is stored in the slicedStr variable and then logged to the console.

Split

The split method is used to divide a string into an array of substrings. It takes a separator as an argument, which specifies the character(s) to use for separating the string. If the separator is not provided, the entire string will be returned as a single element in an array.

let str = "Hello, World!";
let array = str.split(", ");

console.log(array); // Outputs: ["Hello", "World!"]

str is a string. The split method is called on str with ", " as the separator. This divides the string into two substrings “Hello” and “World!”, which are returned as elements in an array. The array is stored in the array variable and then logged to the console.

Replace

The replace method is used to replace a specified value with another value in a string. It returns a new string with some or all matches of a pattern replaced by a replacement. The original string is not modified.

let str = "Hello, World!";
let newStr = str.replace("World", "Universe");

console.log(newStr); // Outputs: "Hello, Universe!"

str is a string. The replace method is called on str with “World” as the pattern to be replaced and “Universe” as the replacement. This results in a new string “Hello, Universe!”, which is stored in the newStr variable and then logged to the console.

ToLowerCase

The toLowerCase method is used to convert a string to lowercase letters. This method does not change the original string, but returns a new string where all the uppercase characters are converted to lowercase.

let str = "Hello, World!";
let lowerCaseStr = str.toLowerCase();

console.log(lowerCaseStr); // Outputs: "hello, world!"

str is a string. The toLowerCase method is called on str, resulting in a new string where all the uppercase characters are converted to lowercase. The new string is stored in the lowerCaseStr variable and then logged to the console.

ToUpperCase

The toUpperCase method is used to convert a string to uppercase letters. This method does not change the original string, but returns a new string where all the lowercase characters are converted to uppercase.

Here’s an example of how to use the toUpperCase method:

let str = "Hello, World!";
let upperCaseStr = str.toUpperCase();

console.log(upperCaseStr); // Outputs: "HELLO, WORLD!"

str is a string. The toUpperCase method is called on str, resulting in a new string where all the lowercase characters are converted to uppercase. The new string is stored in the upperCaseStr variable and then logged to the console.

Trim

The trim method is used to remove whitespace from both ends of a string. This method does not change the original string, but returns a new string with the whitespace removed.

let str = "   Hello, World!   ";
let trimmedStr = str.trim();

console.log(trimmedStr); // Outputs: "Hello, World!"

str is a string with leading and trailing whitespace. The trim method is called on str, resulting in a new string where the whitespace at both ends is removed. The new string is stored in the trimmedStr variable and then logged to the console.

TrimLeft and TrimRight

trimLeft and trimRight methods are used to remove whitespace from the beginning and end of a string respectively. These methods do not change the original string, but return a new string with the whitespace removed.

let str = "   Hello, World!   ";
let trimmedLeftStr = str.trimLeft();
let trimmedRightStr = str.trimRight();

console.log(trimmedLeftStr); // Outputs: "Hello, World!   "
console.log(trimmedRightStr); // Outputs: "   Hello, World!"

In this example, str is a string with leading and trailing whitespace. The trimLeft method is called on str, resulting in a new string where the whitespace at the beginning is removed. Similarly, the trimRight method is called on str, resulting in a new string where the whitespace at the end is removed. The new strings are stored in the trimmedLeftStr and trimmedRightStr variables and then logged to the console.