JavaScript padStart() Method

The padStart() method in JavaScript is used to pad a string with another string or characters at the beginning (left side) until it reaches a specified length. It is often used to ensure that a string has a certain minimum length by adding padding characters.

The syntax for padStart() is as follows:

str.padStart(targetLength [, padString])

• str: The string to pad.
• targetLength: The desired length of the resulting padded string.
• padString (optional): The string or characters to use for padding. If not specified, it defaults to a single space character.

Here’s an example usage of padStart():

const str = '5';
const paddedStr = str.padStart(4, '0');

console.log(paddedStr); // Output: '0005'

In this example, the str variable contains the string '5'. We call the padStart() method on str and provide a targetLength of 4 and a padString of '0'. The resulting padded string is '0005', which has a length of 4 characters.

If the length of the original string is already equal to or greater than the targetLength, padStart() will not perform any padding and simply return the original string:

const str = 'Hello';
const paddedStr = str.padStart(6, '0');

console.log(paddedStr); // Output: 'Hello'

In this case, the length of the original string 'Hello' is already 5, which is greater than the targetLength of 6. Therefore, padStart() does not add any padding and returns the original string 'Hello'.

The padStart() method is useful for formatting and aligning strings, especially when dealing with fixed-width columns or formatting numbers. It allows you to easily add leading zeros or other characters to ensure consistent string lengths.