Introduction to left-pad

The left-pad library is a simple yet highly useful tool for developers that provides the ability to left pad strings with a specific character. This library has gained widespread recognition due to its simplicity and efficiency. In this guide, we will dive deep into various APIs provided by the left-pad library and showcase dozens of examples and a practical application at the end.

Basic Usage

Here is a basic example of how to use left-pad in your project:

  const leftPad = require('left-pad');
  console.log(leftPad('hello', 10, '_'));  // Output: _____hello

API Examples

1. Padding with Different Characters

  console.log(leftPad('world', 8, '*'));  // Output: ***world
  console.log(leftPad('test', 6, '-'));   // Output: --test

2. Padding Numerical Strings

  console.log(leftPad('123', 5, '0'));    // Output: 00123
  console.log(leftPad('45', 4, '_'));     // Output: __45

3. Padding with Multiple Characters

  console.log(leftPad('abc', 7, 'xy'));  // Output: xyxxyabc

4. Padding Empty Strings

  console.log(leftPad('', 5, 'z'));      // Output: zzzzz

5. Long Padding Strings

  console.log(leftPad('short', 25, '#'));      // Output: ####################short

App Example Using left-pad

Finally, let’s present a practical application using left-pad to format numerical IDs consistently within a string length of 6.

  const leftPad = require('left-pad');

  function formatID(id) {
      return leftPad(id.toString(), 6, '0');
  }

  console.log(formatID(35));     // Output: 000035
  console.log(formatID(1234));   // Output: 001234
  console.log(formatID(56789));  // Output: 056789

In this example, the formatID function ensures all IDs are padded to a length of 6 using zeroes. This is especially useful in database applications where consistent formatting of IDs is crucial.

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