Substring

The substring() method in JavaScript extracts a portion of a string from one position to another (exclusive) and returns a new string. If the second position is omitted, it returns characters from the first position to the end of the string.

Syntax

// Returns characters from startIndex to end of string
string.substring(startIndex);

Or alternatively:

// Returns characters from startIndex to endIndex
string.substring(startIndex, endIndex);

Details

• .substring() returns characters from the start index up to, but not including, the character at the end index.

• If the end index is omitted, .substring() returns characters from the start index through the end of the string.

• If the start and end indices are equal, .substring() returns an empty string.

• Indices that are less than zero or are NaN are interpreted as zero.

• Indices that are greater than string.length are treated as string.length.

• If the first argument is greater than the second argument, the first argument is treated as the end index and the second argument is treated as the start index.

Example 1

Using .substring() to display characters from a given string.

const str = 'Codecademy';

console.log(str.substring(0, 4));
console.log(str.substring(4, 0));
console.log(str.substring(-4, 4));
// Output: "Code"

console.log(str.substring(4));
console.log(str.substring(4, 99));
// Output: cademy

Example 2

Using .substring() to display the last 6 characters from a given string.

const str = 'Codecademy';

console.log(str.substring(str.length - 6));
// Output: cademy

Codebyte Example

Run the following code to understand how the .substring() method works:

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