1const expenses = [  
2  { category: 'food', amount: 15 },  
3  { category: 'transport', amount: 25 },  
4  { category: 'entertainment', amount: 40 },  
5];  
6
7const totalAmountByCategory = expenses.reduce((acc, expense) => {  
8  if (!acc[expense.category]) {  
9    acc[expense.category] = 0;  
10  }  
11  acc[expense.category] += expense.amount;  
12  return acc;  
13}, {});  
14
15console.log(totalAmountByCategory);