Multiply Strings LeetCode solution in JavaScript

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var multiply = function (num1, num2) {
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  const m = num1.length;
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  const n = num2.length;
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  const steps = [];
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  let carry = 0;
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  for (let i = m - 1; i >= 0; i -= 1) {
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    const digitOne = parseInt(num1[i]);
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    let step = "0".repeat(m - 1 - i);
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    carry = 0;
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    for (let j = n - 1; j >= 0; j -= 1) {
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      const digitTwo = parseInt(num2[j]);
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      const product = digitOne * digitTwo + carry;
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      const newDigit = product % 10;
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      carry = Math.floor(product / 10);
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      step = newDigit + step;
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    }
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    if (carry > 0) step = carry + step;
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    steps.push(step);
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  }
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  for (let i = 0; i < steps.length - 1; i += 1) {
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    let nextStep = steps[i + 1];
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    let step = steps[i];
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    step = "0".repeat(nextStep.length - step.length) + step;
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    carry = 0;
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    let newStep = "";
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    for (let j = step.length - 1; j >= 0; j -= 1) {
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      const sum = parseInt(nextStep[j]) + parseInt(step[j]) + carry;
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      const digit = sum % 10;
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      carry = Math.floor(sum / 10);
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      newStep = digit + newStep;
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    }
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    if (carry > 0) newStep = carry + newStep;
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    steps[i + 1] = newStep;
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  }
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  let result = steps[steps.length - 1];
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  let leadingZeros = 0;
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  while (leadingZeros < result.length - 1 && result[leadingZeros] === "0") {
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    leadingZeros += 1;
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  }
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  return result.slice(leadingZeros);
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};