How Can I Reverse a String in JavaScript Without Using Built-in Reverse Functions?

In-Place String Reversal in JavaScript

Reversing a string in-place is a common programming task, and JavaScript offers various methods to achieve this. One challenge is to reverse the string without using built-in functions like .reverse() or .charAt().

Approach 1: Array Manipulation

If you can rely on dealing with ASCII characters, you can leverage the following approach:

function reverse(s) {
    return s.split("").reverse().join("");
}

This method splits the string into an array of characters, reverses the array, and joins it back into a string.

Approach 2: Unicode-Aware Array Expansion

For strings containing multi-byte characters (e.g., UTF-16), consider using the array expansion operator:

function reverse(s) {
    return [...s].reverse().join("");
}

Approach 3: Split with Regular Expression

Another Unicode-aware solution using split() involves using a regular expression with the u (Unicode) flag:

function reverse(s) {
    return s.split(/(?:)/u).reverse().join("");
}

Note: These solutions assume a string of ASCII or Unicode code points. If you're dealing with strings containing surrogate pairs or complex characters, more advanced techniques may be required.

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