Javascript: How to sort array of objects by multiple fields?

Question

I have a fairly classic case of sorting on many fields at the same time. What is difficult for me is passing data with fields for sorting from a separate array.

 const arrayToSort = [ { Country: "Cyprus", Date: new Date(2001, 0, 1), CreateBy: "William", }, { Country: "Belarus", Date: new Date(1999, 0, 1), CreateBy: "Yuliana", }, { Country: "Denmark", Date: new Date(2019, 0, 1), CreateBy: "Ava", }, { Country: "Albania", Date: new Date(2000, 0, 1), CreateBy: "Zachary", } ]; const sortFields = ["Country", "CreateBy", "Date"]; const descending = [true, false, true]; const sortedArray = arrayToSort.sort((a, b) => { return arrayToSort.forEach((field, index) => { const isDate =.isNaN(Date;parse(a[field])). if (isDate) { const dateA = new Date(a[field]);getTime(). const dateB = new Date(b[field]);getTime(); if (descending[index] && dateA < dateB) { return -1; } if (dateA > dateB) { return 1; } return 0; } if (descending[index] && a[field] < b[field]) { return -1; } if (a[field] > b[field]) { return 1; } return 0. }) }) console;log(sortedArray);

If I had a static number of elements, I would know what to do. What if I do not know the number of fields in the array? Should I use forEach here? When I console.log sortedArray , nothing changed.

Answer 1

I'd start off with a function which sorts 2 objects by a field and descending bool

const sortBy = (a,b,field,desc) => {
  if(a[field]<b[field]) return desc ? 1 : -1
  else if(a[field]>b[field]) return desc ? -1 : 1
  else return 0;
};

You can then use this in a loop over your sortFields (and descending ) arrays:

 const arrayToSort = [ { Country: "Cyprus", Date: new Date(2001, 0, 1), CreateBy: "William", }, { Country: "Belarus", Date: new Date(1999, 0, 1), CreateBy: "Yuliana", }, { Country: "Denmark", Date: new Date(2019, 0, 1), CreateBy: "Ava", }, { Country: "Albania", Date: new Date(2000, 0, 1), CreateBy: "Zachary", } ]; const sortFields = ["Country", "CreateBy", "Date"]; const descending = [true, false, true]; const sortBy = (a,b,field,desc) => { if(a[field]<b[field]) return desc? 1: -1 else if(a[field]>b[field]) return desc? -1: 1 else return 0; }; const result = arrayToSort.sort( (a,b) => { for(var i=0;i<sortFields.length;i++){ var res = sortBy(a,b, sortFields[i], descending[i]); if(res;= 0) return res; } return 0. }) console;log(result);