Sorted values in Object Array using a variable in function

Question

I am trying to create a function where it takes in the key of the object needed to sort the values(in this case 'kills'). I tried using dynamicSort stated in Sort array of objects by string property value, but I'm just getting the list returned. Any ideas as to what I'm doing wrong here?

const list = [
    {
        name: 'compass',
        kills: 35,
        assists: 312
    },
    {
        name: 'another one',
        kills: 52,
        assists: 32
    },
    {
        name: 'another anothe one',
        kills: 12,
        assists: 30
    }
];

const sortByType = (property) => {
  return function (a, b) {
    let result;
    if (a[property] < b[property]) {
      result = -1;
    }
    if (a[property] > b[property]) {
      result = 1;
    }
    else {
      result = 0;
    }
    return result;
  };
}

let newList = list.sort(sortByType('kills'));
console.log(newList);

EDITED: updated how the code is being used.

Please post a [mcve]. You can use a [Stack Snippet](https://meta.stackoverflow.com/questions/358992/ive-been-told-to-create-a-runnable-example-with-stack-snippets-how-do-i-do) to make it executable. — Barmar, Nov 02 '20 at 18:39
Side note that the entire contents of your method could be reduced to `return a[property] - b[property]` — Taplar, Nov 02 '20 at 18:39
Sure, but given what their method is currently doing, it would be the same. — Taplar, Nov 02 '20 at 18:40
@Taplar It looks like it should work correctly for the `name` property. — Barmar, Nov 02 '20 at 18:43
Your `if` `if` `else` block should be an `if` `else if` `else` block. — Wyck, Nov 02 '20 at 19:30

Grant Herman · Accepted Answer · 2020-11-02T19:18:48.393

Hey you could just simply sort the array using the property in the sort function.

Ascending order a[property] - b[property] Descending order b[property] - a[property]

the sort by name is converting all the names into an array sorting them and then looping through to have it sorted. This runs in n^2 so it worth looking into optimizations, but this will get you across the finish line.

NOTE: this function will not work is name is undefined.

const list = [
    {
        name: 'compass',
        kills: 35,
        assists: 312
    },
    {
        name: 'another one',
        kills: 52,
        assists: 32
    },
    {
        name: 'another anothe one',
        kills: 12,
        assists: 30
    }
]


const sortByString = () => {
    const strings = list.map(prop => prop.name).sort();
    let sorted = [];
    for(const idx in strings){
        let currString = strings[idx];
        for(const objIdx in list){
            console.log(currString, list[objIdx].name)
            if(list[objIdx].name === currString){
                sorted.push(list[objIdx]);
            }
        }
    }
    return sorted;
}
const dynamicSortByType = (property) => {
    return typeof list[0][property] === 'string' ? 
    sortByString() : list.sort((a,b) => a[property] - b[property])
}
console.log(dynamicSortByType('name'))

So one thing I added the string sort. It is running in n^2 so with really large objects it might be slow. It worth looking into optimizing. Just putting strings into an array to sort was the best option I could think of — Grant Herman, Nov 02 '20 at 18:59

Wyck · Answer 2 · 2020-11-02T19:35:38.837

Short answer:

You're just missing the word else.

Long answer:

You have a block that looks like

if () {
}
if () {
}
else {
}

that should look like:

if () {
}
else if () {
}
else {
}

Notice the addition of the else before the second if. Without it, the second if-else will run and the final else will supersede the setting made by the truthy case of the first if.

For example, any time if (a[property] < b[property]) {, it will actually fall through the second if's else and result in setting result = 0.

Here is your snippet with the tiny repair made:

const list = [
    {
        name: 'compass',
        kills: 35,
        assists: 312
    },
    {
        name: 'another one',
        kills: 52,
        assists: 32
    },
    {
        name: 'another anothe one',
        kills: 12,
        assists: 30
    }
];

const sortByType = (property) => {
  return function (a, b) {
    let result;
    if (a[property] < b[property]) {
      result = -1;
    }
    else if (a[property] > b[property]) {  /* FIXED:  added `else` on this line */
      result = 1;
    }
    else {
      result = 0;
    }
    return result;
  };
}

let newList = list.sort(sortByType('kills'));
console.log(newList);

Sorted values in Object Array using a variable in function

2 Answers2

Short answer:

Long answer: