Implement Rand10() Using Rand7() LeetCode solution in JavaScript

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var rand10 = function () {
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  while (true) {
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    const rand49 = (rand7() - 1) * 7 + rand7();
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    if (rand49 <= 40) return (rand49 % 10) + 1;
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    const rand9 = rand49 - 40;
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    const rand63 = (rand9 - 1) * 7 + rand7();
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    if (rand63 <= 60) return (rand63 % 10) + 1;
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    const rand3 = rand63 - 60;
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    const rand21 = (rand3 - 1) * 7 + rand7();
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    if (rand21 <= 20) return (rand21 % 10) + 1;
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  }
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};