String.prototype.padEnd()

Summary: in this tutorial, you will learn how to use the JavaScript String padEnd() method to pad a string from the end to a certain length.

Introduction to the JavaScript padEnd() method

The padEnd() method pads the end of a string with another string until the resulting string reaches a specified length.

Here’s the syntax of the padEnd() method:

string.padEnd(targetLength, padString)Code language: CSS (css)

In this syntax:

• targetLength is the desired length of the resulting string after the input string is padded. If the targetLength is less than or equal to the length of the input string, the padEnd() method returns the input string as-is.
• The padString is an optional parameter, specifying the string to pad the current string with. The padString defaults to a space character (' '). This means that the padEnd() method will use a space character to pad the input string if you skip the padString argument. If the padString is too long to stay within the targetLength, the padEnd() method will truncate it.

In practice, you’ll find the padEnd() useful in various scenarios, such as formatting text, aligning data, and more.

Note that to pad from the beginning of a string, you use the padStart() method.

JavaScript padEnd() method examples

Let’s take some examples of using the padEnd() method.

1) Basic JavaScript padEnd() method example

The following example uses the padEnd() method to pad a string from the end of a specified string:

let s = 'ha'.padEnd(10, 'ha');
console.log({ s });

s = 'yahoo'.padEnd(20, 'o');
console.log({ s });
Code language: JavaScript (javascript)

Output:

{ s: 'hahahahaha' }
{ s: 'yahooooooooooooooooo' }Code language: CSS (css)

2) Formating table data

When developing CLI applications, you may want to display data in table format. To ensure each column has a consistent width, you can use the padEnd() method. For example:

const formatTable = (data, cellWidth = 20) => {
  data.forEach((row) => {
    let formattedRow = row.map((cell) => cell.padEnd(cellWidth)).join('|');
    console.log(formattedRow);
  });
};

let data = [
  ['Name', 'Age', 'City'],
  ['Alice', '30', 'New York'],
  ['Bob', '25', 'San Francisco'],
  ['Charlie', '35', 'Los Angeles'],
];

formatTable(data);Code language: JavaScript (javascript)

Output:

Name                |Age                 |City
Alice               |30                  |New York
Bob                 |25                  |San Francisco
Charlie             |35                  |Los AngelesCode language: Shell Session (shell)

Summary

• Use the padEnd() method to pad from the end of a string with another string until the resulting string reaches a certain length.