Remove Alternating Commas from An Object contained in an Array in JavaScript

Question

If I have an array such as this:

let arr = [{name: "Cool", subject_schedule: ["So","3610A", "USA", "1010"]}, {name: "Lots", subject_schedule: ["Dog","1310A", "CAN", "2020"]} ];

How can I make it so the "subject_schedule" property in each of the objects in the array is combined into pairs such as:

let result = [{name: "Cool", subject_schedule: ["So 3610A", "USA 1010"]}, {name: "Lots", subject_schedule: ["Dog 1310A", "CAN 2020"]} ];

phi-rakib · Accepted Answer · 2020-11-08 01:40:44Z

2

You could use Array.prototype.map() method and for pairing subject_schedule array use a simple recursive function. Map method returns a new array by calling the provided function for each item of the array.

const data = [
  { name: 'Cool', subject_schedule: ['So', '3610A', 'USA', '1010'] },
  { name: 'Lots', subject_schedule: ['Dog', '1310A', 'CAN', '2020'] },
];

const makePair = (arr, result = []) => {
  if (arr.length === 0) return result;
  result.push(arr.slice(0, 2).join(' '));
  return makePair(arr.slice(2), result);
};

const ret = data.map((x) => ({
  ...x,
  subject_schedule: makePair(x.subject_schedule),
}));
console.log(ret);

edited Nov 8, 2020 at 1:40

answered Nov 8, 2020 at 1:12

phi-rakib

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1 Comment

Vivek22 Over a year ago

what a nice way to use makePair recursion here. good thought. without looking at the solution, i gave it a try and ended up with almost similar to yours without recursion. but, yours is very neat. arr.map((item) => { const{ subject_schedule } = item; const combined_subject_schedule = []; for(i = 0; i<subject_schedule.length; i+=2) { combined_subject_schedule.push(subject_schedule.slice(i, i+2).join(' ')); } return {...item, subject_schedule: combined_subject_schedule} })

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