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JavaScript

Fareez Ahmed
Fareez Ahmed
12,728 Points
Posted by Fareez Ahmed
Fareez Ahmed
12,728 Points

Recursion Practice

I'm trying to practice recursion by building a function that puts each element of a list into it's own list, but I'm getting stuck. where am I going wrong?

function ownList(arr){
  if (arr.length >= 1) {
    arr[0] = [arr[0]];
    return;
  } else {
    return arr[0].concat(ownList(arr.slice(1)));
  }

}
var arr = [1,2,3]
console.log(ownList(arr))// returns []
//should return [[1],[2],[3]]

1 Answer

Seth Shober
Seth Shober
30,240 Points
Seth Shober
Seth Shober
30,240 Points

I'm a little confused as to what you are trying to do/achieve. Could you be a little more explicit? Here is a classic example I put together for recursion and fizzbuzz which may turn on the lightbulb for you. Please note that though this is a valid way to do this, I may not choose to use recursive in this situation vs more traditional conditionals like if...else, ternary, or switch. 

function fizzBuzzRecursive(start, end) {

    // base check
    if (start > end || typeof start != 'number' || typeof end != 'number') return
    // do fizzbuzz
    if ( start % 3 == 0 && start % 5 == 0 ) console.log('FizzBuzz')
    else if ( start % 3 == 0 ) console.log('Fizz')
    else if ( start % 5 == 0 ) console.log('Buzz')
    else console.log(start)
    // call recursively
    fizzBuzzRecursive(start + 1, end) // cannot use ++

}

Here is a jsperf showing comparisons if interested.