Extracting a substring from a string

String slice: String.slice()

The slice() method in JavaScript is used to extract a portion of a string and return it as a new string without modifying the original string.

Syntax:

string.slice(start, end)

The parameters

1. start: The index at which the extraction will begin. If negative, it counts from the end of the string.

2. end (optional): The index at which the extraction will end. If not specified, the extraction goes to the end of the string. If negative, it counts from the end of the string.

Note

The character at the end index is not included in the returned string.

Return Value:

The slice() method returns a new string representing the extracted portion of the original string.

Example

// Using only the start parameter
const str = 'Hello, world!';

const slicedString = str.slice(7);
console.log(slicedString);
// Output: "world!"

In the example above, The slice() method extracts the portion of the string starting from index 7 to the end (str.length - 1). The extracted substring, 'world!', is stored in the variable slicedString.

// Using both start and end parameters
const str = 'Hello, world!';

const slicedString = str.slice(1, 4);
console.log(slicedString);
// Output: "ell"

In the example above, The slice() method extracts the portion of the string starting from index 1 and ending at index 4(exclusive). The extracted substring, 'ell', is stored in the variable slicedString.

// Using negative indices with only start parameter
const str = 'Hello, world!';

const slicedString = str.slice(-6);
console.log(slicedString);
// Output: "world!"

In the example above, The slice() method extracts the portion of the string starting from the 6th character from the end to the end of the string. The extracted substring, 'world!', is stored in the variable slicedString.

// Using negative indices with both start and end parameter
const str = 'Hello, world!';

const slicedString = str.slice(-6, -3);
console.log(slicedString);
// Output: "wor"

In the example above, The slice() method extracts the portion of the string starting from the 6th character from the end to the 3rd character from the end (exclusive). The extracted substring, 'wor', is stored in the variable slicedString.

By using the String.slice() method, you can efficiently extract substrings from a given string based on the specified indices, noting that the character at the end index is not included in the returned string.