Can someone help me understand why this function is giving me this output?

function mergeSort(array) {
    if (array.length === 1) return array

    leftArraySorted = mergeSort(array.slice(0, (Math.floor(array.length / 2))))
    rightArraySorted = mergeSort(array.slice(Math.floor(array.length / 2)))

    let a = 0
    let b = 0
    const mergedSortedArray = []

    for (let i = 0; i < array.length; i  ) {
      if (leftArraySorted[a] < rightArraySorted[b]) {
        mergedSortedArray.push(leftArraySorted[a])
        a  = 1
      }

      else if (leftArraySorted[a] > rightArraySorted[b]) {
        mergedSortedArray.push(rightArraySorted[b])
        b  = 1
      }

      else if (leftArraySorted[a] === rightArraySorted[b]) {
        mergedSortedArray.push(leftArraySorted[a])
        a  = 1
      }

      else if (leftArraySorted[a] === undefined) {
        mergedSortedArray.push(rightArraySorted[b])
        b  = 1
      }

      else if (rightArraySorted[b] === undefined) {
        mergedSortedArray.push(leftArraySorted[a])
        a  = 1
      }
    }
    return mergedSortedArray
}

console.log(mergeSort(6, 3, 5) is outputting [3, 3 ,5], Why? Already went trough the code 50 times and can't figure out what is causing this.

CodePudding user response：

You should use the let keyword to declare those two local arrays

let leftArraySorted = mergeSort(array.slice(0, (Math.floor(array.length / 2))))
let rightArraySorted = mergeSort(array.slice(Math.floor(array.length / 2)))