Array to List Javascript

Question

I am trying to convert an array to list(containing objects) and first object is connected to next pair value.

This is what I have done so far:

var myArray = [1,2,3] ;
function arrayToList()
{
    var myList = Object.keys(myArray).map(function(key){

        return { value: myArray[key],rest:myArray[key]}    

    });
    console.log(myList);
}
arrayToList(myArray);

This should return Like this:

var list = {
  value: 1,
  rest: {
    value: 2,
    rest: {
      value: 3,
      rest: null
    }
  }
};

, when given an array of [1,2,3]

instead of rest being rest:myArray[key], call arrayToList() again - but give an offset so you will eventually stop recursing. — theGleep
– theGleep, Commented Oct 17, 2017 at 15:07
Object.keys(myArray) makes no sense since you have an array, not an object. — epascarello
– epascarello, Commented Oct 17, 2017 at 15:15
What would you want the output to be when the array is empty? Should it just return null? — castletheperson
– castletheperson, Commented Oct 17, 2017 at 19:50

castletheperson · Accepted Answer · 2017-10-17 15:18:19Z

3

Use Array#reduceRight

function arrayToList(arr) {
  return arr.reduceRight((rest, value) => ({ value, rest }), null);
}

console.log(arrayToList([1, 2, 3]));

edited Oct 17, 2017 at 15:18

answered Oct 17, 2017 at 15:12

castletheperson

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2 Comments

Nauman Mughal Over a year ago

It is working but when you expand the 2nd value in browser it disappears and all you can see it value 1 and value 3. One more thing if you want to do the reverse for List to Array what one can do ? The output for the first one is {value: 1, rest: {…}}rest: rest: rest: nullvalue: 3__proto__: Objectvalue: 2__proto__: Objectvalue: 1__proto__: Object

Vasan Over a year ago

@NaumanMughal The value doesn't disappear. The browser displays it below the expanded object. If you want, you could do a console.log(JSON.stringify(arrayToList([1, 2, 3]))); for more clarity.

Mark · Accepted Answer · 2017-10-17 15:53:17Z

1

This lends itself well to a simple 1-line recursive function (especially nice with es6):

function tolist([value, ...rest]) {
      return {value, rest: rest.length ? tolist(rest): null}
}

console.log(tolist([0, 2, 3, 4]))

edited Oct 17, 2017 at 15:53

answered Oct 17, 2017 at 15:38

Mark

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