How to sort an object array with custom order?

Question

I have an object array like this:

[
    {keyword: 'E', value: '5'},
    {keyword: 'C', value: '3'},
    {keyword: 'B', value: '2'},
    {keyword: 'D', value: '4'},
    {keyword: 'A', value: '1'},
    {keyword: 'F', value: '6'},
    ...
]

I receive this array from other places and I have no control over the source, also the order that it comes can be completely random.

Now I want to sort the array with ascending order on keyword, with the exception of swapping 2 objects. I know the keyword of the object that I want to swap, let say C, and D in the above array. So the final result I want it to be like this:

[
    {keyword: 'A', value: '1'},
    {keyword: 'B', value: '2'},
    {keyword: 'D', value: '4'},
    {keyword: 'C', value: '3'},
    {keyword: 'E', value: '5'},
    {keyword: 'F', value: '6'},
    ...
]

I have to following code, but I don't know where to put the rest of the code. Please help!

myArray.sort(function(a, b){
     return a.keyword.toLowerCase().localeCompare(b.keyword.toLowerCase());
});

Taplar · Accepted Answer · 2018-05-31 20:06:52Z

2

var myArray = [
  {keyword: 'E', value: '5'},
  {keyword: 'C', value: '3'},
  {keyword: 'B', value: '2'},
  {keyword: 'D', value: '4'},
  {keyword: 'A', value: '1'},
  {keyword: 'F', value: '6'}
];

var specialKeywords = [ 'C', 'D' ];

myArray.sort(function(a, b){
  //if the two being compared are 'C' and 'D', treat them special
  if (specialKeywords.indexOf(a.keyword) +1
  && specialKeywords.indexOf(b.keyword) +1) {
    //if a is 'C', it needs to be greater than 'D'
    if (a.keyword = 'C') return 1;
    else return -1;
  } else {
    //one of the elements is not 'C' or 'D', process normally.
    return a.keyword.toLowerCase().localeCompare(b.keyword.toLowerCase());
  }
});

console.log(myArray);

answered May 31, 2018 at 20:06

Taplar

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1 Comment

MayDay Over a year ago

Works as expected! I like this one to put all the logic inside sort function. Thank you!

Nishant Dixit · Accepted Answer · 2018-05-31 20:11:03Z

0

var data = [
    {keyword: 'E', value: '5'},
    {keyword: 'C', value: '3'},
    {keyword: 'B', value: '2'},
    {keyword: 'D', value: '4'},
    {keyword: 'A', value: '1'},
    {keyword: 'F', value: '6'},
]

var swapData =['C','D'];

data = data.sort((a,b)=> a.keyword < b.keyword?-1:1);

var [first,second] = [data.findIndex((val)=>val.keyword == swapData[0]),data.findIndex((val)=>val.keyword == swapData[1])];

var temp = data[first];
data[first] = data[second];
data[second]  = temp;

console.log(data);

answered May 31, 2018 at 20:11

Nishant Dixit

5,5125 gold badges22 silver badges32 bronze badges

Comments

bajro · Accepted Answer · 2018-05-31 21:18:31Z

Here is an example where currying is being used to first sort the array and then swap two objects by providing two keywords if both of them exist in the sorted array.

const a = [
    {keyword: 'E', value: '5'},
    {keyword: 'C', value: '3'},
    {keyword: 'B', value: '2'},
    {keyword: 'D', value: '4'},
    {keyword: 'A', value: '1'},
    {keyword: 'F', value: '6'},
]


//Using currying where the function is broken down into a series of functions
const sortSwap = (arrayToSort) => {
  //first sort it
  const sortedArray = arrayToSort.sort((a,b) => a.keyword.toLowerCase() > b.keyword.toLowerCase());
  return (swap1, swap2) => {
    //now swap it
    const item1 = sortedArray.findIndex(elem => elem.keyword === swap1);
    const item2 = sortedArray.findIndex(elem => elem.keyword === swap2);
    //if actually both keywords are existing in the array, proceed to swap
    if (item1 >= 0 && item2 >= 0) {
    const temp = sortedArray[item1];
    sortedArray[item1] = sortedArray[item2];
    sortedArray[item2] = temp;
    }
    return sortedArray;
  }
}


//call the function by using currying 
console.log(sortSwap(a)('A', 'C'));

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