Arithmetic Slices LeetCode solution in JavaScript

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/**
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 * @param {number[]} nums
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 * @return {number}
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 */
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var numberOfArithmeticSlices = function (nums) {
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  if (nums.length < 3) return 0;
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  const diff = [];
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  /* fill our array of differences */
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  for (let i = 1; i < nums.length; i++) {
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    diff.push(nums[i] - nums[i - 1]);
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  }
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  /* if the first two numbers of our difference array are equal
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   * then set our multiplier to 1
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   * and also set our "previous" variable to 1
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   * otherwise set both to 0 representing no sequence found yet
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   */
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  let multiplier = diff[1] === diff[0] ? 1 : 0;
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  let dp = diff[1] === diff[0] ? 1 : 0; // our "previous" variable
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  /* loop thru our differences from idx 2 (0 and 1 have been
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   * accounted for),
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   * and check for continuing sequences
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   */
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  for (let i = 2; i < diff.length; i++) {
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    if (diff[i] === diff[i - 1]) {
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      // if equal, increment our multiplier
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      multiplier++;
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    } else {
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      // if not equal, set our multiplier back to 0
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      multiplier = 0;
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    }
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    dp = dp + 1 * multiplier; // recurrence relation
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  }
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  return dp; // our "previous" variable
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};