Get the last N characters of a String in JavaScript

Get the last N characters of a String #

Pass -N as an argument to the slice() method to get the last N characters of a string.

For example, str.slice(-2) returns the last 2 characters of the string.

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const str = 'bobbyhadz.com';

// ✅ get the last 2 characters of a string
const last2 = str.slice(-2);
console.log(last2); // 👉️ om

// ✅ get the last 3 characters of a string
const last3 = str.slice(-3);
console.log(last3); // 👉️ com

// ✅ get the last 4 characters of a string
const last4 = str.slice(-4);
console.log(last4); // 👉 .com

The String.slice method extracts a section of a string and returns it, without modifying the original string.

The String.slice() method takes the following arguments:

When only a single argument is passed to the String.slice() method, the slice goes to the end of the string.

Make sure to assign the result of calling the slice() method to a variable as the method doesn't change the original string.

The String.slice() method can be passed negative indexes to count backward.

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const str = 'bobbyhadz.com';

console.log(str.slice(-2)); // 👉️ om

console.log(str.slice(-5)); // 👉️ z.com

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const str = 'bobbyhadz.com';

const last3 = str.slice(-3); // 👉️ com
console.log(last3);

const last3Again = str.slice(str.length - 3);
console.log(last3Again); // 👉️ com

In both examples, we tell the slice method to copy the last 3 characters of the string into a new string.

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const str = 'bobbyhadz.com';

const last100 = str.slice(-100);
console.log(last100); // 👉️ bobbyhadz.com

In this example, we tried to get the last 100 characters of a string that only contains 13 characters.

As a result, the slice method returned a copy of the entire string.

If you have to do this often, define a reusable function.

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function getLastNchars(str, n) {
  return str.slice(-n);
}

const str = 'bobbyhadz.com';

// ✅ get the last 2 characters of a string
console.log(getLastNchars(str, 2)); // 👉️ om

// ✅ get the last 3 characters of a string
console.log(getLastNchars(str, 3)); // 👉️ com

// ✅ get the last 4 characters of a string
console.log(getLastNchars(str, 4)); // 👉️ .com

The getLastNchars function takes a string and N as parameters and returns the last N characters of the string.

Get the last N characters of a string using String.substring #

Pass a start index of str.length - N to the String.substring() method to get the last N characters of a string.

For example, str.substring(str.length - 3) returns the last 3 characters of the string.

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function getLastNchars(str, n) {
  return str.substring(str.length - n);
}

const str = 'bobbyhadz.com';

// ✅ get the last 2 characters of a string
console.log(getLastNchars(str, 2)); // 👉️ om

// ✅ get the last 3 characters of a string
console.log(getLastNchars(str, 3)); // 👉️ com

// ✅ get the last 4 characters of a string
console.log(getLastNchars(str, 4)); // 👉️ .com

The String.substring() method returns a slice of the string from the start index to the excluding end index.

The method takes the following parameters:

If no end index is specified the slice goes to the end of the string.

The String.substring() method doesn't support negative values to count backward, so we had to calculate the start index based on the string's length.

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const str = 'bobbyhadz.com';

// 👇️ om
console.log(str.substring(str.length - 2));

There are a couple of differences between the String.substring() and the String.slice() methods:

• The substring() method swaps its start and end index if the start index is greater than the end index. The slice() method returns an empty string in this case.

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const str = 'bobby';

console.log(str.substring(3, 0)); // 👉️ bob

console.log(str.slice(3, 0)); // 👉️ ''

• If either of both arguments passed to substring() are negative, they are treated as if they were 0.

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const str = 'bobby';

console.log(str.substring(-3)); // 👉️ bobby

console.log(str.slice(-3)); // 👉️ bby

When given a negative index, the slice() method counts backward from the end of the string to find the indexes.

For these reasons, it is recommended to use the String.slice() method to get the last N characters of a string.

The slice method works in a more predictable manner.