Largest Number After Mutating Substring LeetCode solution in JavaScript

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var maximumNumber = function (num, change) {
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  const digits = num.split("");
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  let started = false;
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  for (let i = 0; i < digits.length; ++i) {
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    const origDig = digits[i];
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    const changeDig = change[origDig];
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    if (changeDig > origDig) {
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      started = true;
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      digits[i] = changeDig;
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    } else if (changeDig < origDig && started) {
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      break;
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    }
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  }
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  return digits.join("");
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};