Quicksort Result is a String (Resolved)

JavaScript
1

I’m having with my quickSort function returning a string instead of an array. Any advice on how to properly return the values created by the recursion function?

let log = console.log

function quickSort(arr) {
    
    let localArray = arr.slice()
    
    function recursion (array) {
        if (array.length<2) {return array}
        let lowArray = []
        let highArray = []
        let pivot = array[0]
        
        for (let i=1;i<array.length;i++) {
        if (array[i] < pivot) {lowArray.push(array[i])}    
        
        else if (array[i] > pivot) {highArray.push(array[i])}
        }
        return recursion(lowArray) + pivot + recursion(highArray)
        
    }
    
    return recursion(localArray)
    
}

let r = quickSort([4,2,3,6,5,8,7,9,0,1])
log(r)
log(typeof r)
2

maybe run parseInt() on your return value to change it from a string to a number?

what error are you getting exactly?
or rather what problems are you having?

3 
return recursion(lowArray) + pivot + recursion(highArray)

the + operator is what is changing your array to a string, this is a case of type coercion that is giving unexpected results.
Type coercion explained:






you need a method that chain array together, for example concat()

2 Likes
4

Thanks for the feedback, the concat method did the trick. Changing this line

return recursion(lowArray) + pivot + recursion(highArray)

to this

 return Array.prototype.concat(recursion(lowArray), pivot, recursion(highArray))

made the quickSort work as intended. Thanks!

5

But you have not read the documentation, because that’s not how it is described there

6

Well, unfortunately reading the documentation and understanding the documentation aren’t synonymous lol. I’ll read it again.

7

You call concat on an array
arr1.concat(arr2,arr3)