Multiply Strings

Problem statement

Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.

Note: You must not use any built-in BigInteger library or convert the inputs to integer directly.

Example 1:

Input: num1 = "2", num2 = "3"Output: "6"

Example 2:

Input: num1 = "123", num2 = "456"Output: "56088"

Constraints:

• 1 <= num1.length, num2.length <= 200
• num1 and num2 consist of digits only.
• Both num1 and num2 do not contain any leading zero, except the number 0 itself.

My solution

/**
 * @param {string} num1
 * @param {string} num2
 * @return {string}
 */
var multiply = function(num1, num2) {
    if (num1 == "0" || num2 === "1") {
        return num1;
    }
    if (num2 === "0" || num1 === "0") {
        return num2;
    }
    
    let carry = 0;
    let sum = 0;
    
    let results = Array.from({
        length: num1.length + num2.length
    }, () => 0)
    
    let i;
    let j
    
    for (i = num1.length - 1; i >= 0; i--) {
        carry = 0;
        for (j = num2.length - 1; j >= 0; j--) {
            sum = num2[j] * num1[i] + carry + results[i + j + 1];
            // console.log(`${i}:${j} => ${sum}`)
            carry = Math.floor(sum / 10);
            results[i + j + 1] = sum % 10;
        }
        // console.log(`${i}:${j}`)
        results[i + j + 1] = carry;
    }
    
    console.log(results)
    
    if (results[0] === 0) {
        results.shift();
    }
    return results.join("")
};