如何找到 map 中值的总和和平均值？

Question

My goal is to add the numerical values in this map and divide them by the size of the map. The result is merely the numbers without being added. Here's how my code looks like as of the moment:

const problem2 = new Map();
problem2.set('Julie', 13);
problem2.set('Jojo', 10);
problem2.set('Polly', 10);
problem2.set('Jack', 10);
problem2.set('Bruce', 10);

let sum = "";
for (const value of problem2.values()){
   sum +=  parseInt (value, 10) +"\n";
};

sum; 

Answer 1

You can use forEach and size property

let sum = 0;
problem2.forEach(value => sum += value); // value is problem

let average = sum / problem2.size

Answer 2

You should not be concatenating the string "\n" and sum should be initialized to 0 as you are working with numbers. The average is the sum divided by the number of values in the Map .

 const problem2 = new Map(); problem2.set('Julie', 13); problem2.set('Jojo', 10); problem2.set('Polly', 10); problem2.set('Jack', 10); problem2.set('Bruce', 10); let sum = 0; for (const value of problem2.values()){ sum += value; }; console.log('Sum:',sum); console.log('Average:', sum / problem2.size);

Answer 3

Go with foreach over the map and sum up. For avg divide through mapsize.

 const problem2 = new Map(); problem2.set('Julie', 13); problem2.set('Jojo', 10); problem2.set('Polly', 10); problem2.set('Jack', 10); problem2.set('Bruce', 10); let sum = 0; problem2.forEach(value => sum += value); console.log('Sum: ' + sum); console.log('Average: ' + (sum / problem2.size));

Answer 4

You can convert the Map to an Array so you can use the Array.reduce method.

 const problem2 = new Map(); problem2.set('Julie', 13); problem2.set('Jojo', 10); problem2.set('Polly', 10); problem2.set('Jack', 10); problem2.set('Bruce', 10); const { sum, avg } = [...problem2] // convert Map to Array.reduce((result, [, value]) => { result.sum += value; result.avg = result.sum / problem2.size; return result; }, { sum: 0, avg: 0 }); console.log({ sum, avg }); // { sum: 53, avg: 10.6 }