partitions of a number in javascript

gistfile1.js

const reducer = (accumulator, currentValue) => accumulator + currentValue;

const hasElementGreaterThanOne = (array = []) => {
  let begin = array.length - 2;
  let result = false;
  if (begin > 0) {
    for (let i = begin; i > 0; i--) {
      if (array[i] > 1) {
        result = i;
        break;
      }
    }
  }
  return result;
};

function part(num1) {
  let a = num1;
  let singleSum = [];
  let result = [];
  let b;
  while (a > 0) {
    singleSum.push(a);
    if (singleSum.reduce(reducer) === num1) {
      result.push([...singleSum]);
      if (singleSum[singleSum.length - 1] > 1) {
        a = singleSum[singleSum.length - 1] - 1;
        singleSum.pop();
      } else if (
        singleSum[singleSum.length - 1] === 1 &&
        hasElementGreaterThanOne(singleSum)
      ) {
        let idx = hasElementGreaterThanOne(singleSum);
        singleSum = [...singleSum.slice(0, idx + 1)];
        a = singleSum[singleSum.length - 1] - 1;
        singleSum.pop();
      } else if (singleSum[0] >= 1) {
        a = singleSum[0] - 1;
        singleSum = [];
      } else {
        a--;
        singleSum = [];
      }
    } else if (singleSum.reduce(reducer) < num1) {
      if (singleSum.length < num1) {
        continue;
      } else if (singleSum.length === num1) {
        singleSum.pop();
        continue;
      }
    } else if (singleSum.reduce(reducer) > num1) {
      singleSum.pop();
      a--;
    }
  }
  return result;
}