Implementing String.prototype.trim in JavaScript

The trim() method is a built-in JavaScript function that removes whitespace from both ends of a string. This challenge asks you to implement this functionality yourself, providing a deeper understanding of string manipulation and algorithm design. Implementing trim() is a common task and understanding how it works is a valuable skill.

Problem Description

Your task is to implement a trim function that extends the JavaScript String.prototype with a trim method. This method should remove all leading and trailing whitespace characters from a string. Whitespace characters include spaces, tabs (\t), newlines (\n), carriage returns (\r), and form feeds (\f). The method should return a new string with the whitespace removed, leaving the original string unchanged.

Key Requirements:

• Extend String.prototype: The solution must add a trim method directly to the String prototype, making it available for all strings.
• Remove Leading and Trailing Whitespace: The method must remove whitespace from the beginning and end of the string.
• Whitespace Definition: Whitespace characters are defined as spaces, tabs (\t), newlines (\n), carriage returns (\r), and form feeds (\f).
• Immutability: The original string should not be modified. The method must return a new string.
• Handle Empty Strings: The method should correctly handle empty strings.
• Handle Strings with Only Whitespace: The method should correctly handle strings containing only whitespace characters.

Examples

Example 1:

Input: "  Hello, world!  "
Output: "Hello, world!"
Explanation: Leading and trailing spaces are removed.

Example 2:

Input: " \tHello\n, world!\r\f "
Output: "Hello, world!"
Explanation: All leading and trailing whitespace characters (space, tab, newline, carriage return, form feed) are removed.

Example 3:

Input: ""
Output: ""
Explanation: An empty string remains an empty string.

Example 4:

Input: "   "
Output: ""
Explanation: A string containing only whitespace becomes an empty string.

Example 5:

Input: "Hello, world!"
Output: "Hello, world!"
Explanation: A string with no leading or trailing whitespace remains unchanged.

Constraints

• The input string will be a standard JavaScript string.
• The method must be implemented efficiently, avoiding unnecessary iterations or string allocations. While performance isn't the primary focus, avoid grossly inefficient solutions.
• The solution must be compatible with all modern JavaScript environments.

Notes

• Consider using regular expressions for a concise solution, but be mindful of potential performance implications.
• Think about how to efficiently find the first non-whitespace character from the beginning and the last non-whitespace character from the end of the string.
• Remember that you are modifying the String.prototype, so be careful not to introduce any conflicts with existing methods. Using String.prototype.trim = ... is the correct way to extend the prototype.
• Test your solution thoroughly with various edge cases, including empty strings, strings with only whitespace, and strings with mixed whitespace and non-whitespace characters.