AI solution for JavaScript Coding Question on BFE.dev
75. implement BigInt subtraction

One possible implementation of the subtract function without using BigInt is to:

1. Pad the input strings with leading zeros to equal lengths.
2. Starting from the rightmost digit, subtract each pair of digits between the input strings and keep track of any borrow.
3. If a borrow occurs, decrement the next left digit of the minuend by 1 and add 10 to the current digit.
4. Remove any leading zeros in the resulting string.

Here's the code:

function subtract(a, b) {  // 1. Pad input strings with leading zeros  const maxLength = Math.max(a.length, b.length);  a = a.padStart(maxLength, '0');  b = b.padStart(maxLength, '0');    // 2. Subtract each pair of digits and handle borrow  let result = '';  let borrow = 0;  for (let i = maxLength - 1; i >= 0; i--) {    const diff = Number(a[i]) - Number(b[i]) - borrow;    if (diff < 0) {      borrow = 1;      result = (10 + diff).toString() + result;    } else {      borrow = 0;      result = diff.toString() + result;    }  }    // 3. Remove leading zeros  while (result.startsWith('0') && result.length > 1) {    result = result.slice(1);  }  return result;}

This implementation works by comparing each digit of the two input strings and subtracting them while keeping track of any borrow. The result is then constructed by appending each computed difference to the left, and leading zeros are removed.