JavaScript String Extraction Methods

Sometimes we do not need the entire string. Instead, we may need only a specific part of it.

For example:

Extracting a username from an email address
Extracting a file extension
Extracting a date from a timestamp
Splitting a sentence into words

For such tasks, JavaScript provides String Extraction Methods.

In this article, we will learn the most commonly used extraction methods with examples and outputs.

slice()

The slice() method extracts a portion of a string and returns it as a new string.

The original string remains unchanged.

Syntax

string.slice(startIndex, endIndex)

Arguments

startIndex: The position where extraction starts.

endIndex (Optional): The position where extraction stops. The character at this position is not included.

Example

let text = "JavaScript";
console.log(text.slice(0, 4));

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Output

Java

Extraction starts from index 0 and stops before index 4.

Example

let text = "JavaScript";
console.log(text.slice(4));

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Output

Script

When endIndex is not provided, extraction continues until the end of the string.

Negative Index Example

let text = "JavaScript";
console.log(text.slice(-6));

Output

Script

Negative values count from the end of the string.

substring()

The substring() method extracts characters between two positions.

It is similar to slice(), but it does not support negative indexes.

Syntax

string.substring(startIndex, endIndex)

Arguments

startIndex: Starting position.

endIndex (Optional): Ending position. This position is not included in the result.

Example

let text = "JavaScript";
console.log(text.substring(0, 4));

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Output

Java

Example

let text = "JavaScript";
console.log(text.substring(4));

Output

Script

Difference Between slice() and substring()

Feature	slice()	substring()
Negative Index Support	Supports negative indexes	Does not support negative indexes
Start > End	Returns an empty string	Automatically swaps the values
Syntax	slice(start, end)	substring(start, end)
Example	text.slice(-6)	text.substring(-6)
Best Use Case	When you need to count from the end of a string	When working with positive indexes only

let text = "JavaScript";
console.log(text.slice(-6));      // Script
console.log(text.substring(-6));  // JavaScript

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split()

The split() method converts a string into an array.

It separates the string based on a specified separator.

Syntax

string.split(separator, limit)

Arguments

separator: The character or text used to split the string.

limit (Optional): Maximum number of elements to return.

Example

let text = "HTML,CSS,JavaScript";
console.log(text.split(","));

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Output

[“HTML”, “CSS”, “JavaScript”]

Example

let text = "HTML CSS JavaScript";
console.log(text.split(" "));

Output

[“HTML”, “CSS”, “JavaScript”]

Example Using Limit

let text = "HTML,CSS,JavaScript,React";
console.log(text.split(",", 2));

Output

[“HTML”, “CSS”]

Only the first two elements are returned.

Example: Extract Username from Email

let email = "ritik@gmail.com";
console.log(email.split("@")[0]);

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Output

ritik

Practical Example: Extract Domain Name

let email = "ritik@gmail.com";
console.log(email.split("@")[1]);