Javascript es6 - How to remove duplicates in an array of objects, except the last duplicate one?

Question

I have an array:

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 1         


        

Answer 1

Use reduce to convert it an object first to remove the duplicates and last duplicate should override the previous one

var obj = arr.reduce( ( acc, c ) =>  Object.assign(acc, {[c.price]:c.amount}) , {});

Convert it back to array and sort the same

var output = Object.keys( obj )
              .map( s => ({ price : s, amount : obj[ s ] }) )
              .sort( ( a, b )  => b.price - a.price );

Demo

var arr = [
  {price: 5, amount: 100},
  {price: 3, amount: 50},
  {price: 10, amount: 20},
  {price: 3, amount: 75},
  {price: 7, amount: 15},
  {price: 3, amount: 65},
  {price: 2, amount: 34}
];
var obj = arr.reduce( ( acc, c ) =>  Object.assign(acc, {[c.price]:c.amount}) , {});
var output = Object.keys( obj )
              .map( s => ({ price : s, amount : obj[ s ] }) )
              .sort( ( a, b )  => b.price - a.price );
console.log( output );