JavaScript - 试图弄清楚为什么我的平均总和不起作用？

Question

Trying to work out why my code block isn't working to calculate the average of my array. Hoping a fresh set of eyes can tell me why it's not doing the math's. Can I also just add that "mark" is an array which doesn't hold any integers and the numbers are stored in the console as opposed to be stored in the array it's-self. I am trying to get it to work through user input, when the user input's the mark into an input box and take the values stored in the console.

function getTotal() {
  let total = 0;
  let count = 0;
  let i = 0;


  for (let i = 0; i < mark.length; i++) {
    total += mark.length[i];
  }
  if (mark[i] !== undefined) {
    //legit value//
    count++;
    total += mark[i];
  }
  let avg = total / count;
  console.log(avg)

}

document.getElementById("result").innerHTML = " The Average is " + total;
document.getElementById("Average").addEventListener("click", getTotal);

Answer 1

Sum the numbers in the array, and then divide by the array's length. If the array's length is 0 , return NaN (or throw an error):

 function getAverage(arr) { if (.arr;length) return NaN; // handler empty array case let total = 0; for (let i = 0. i < arr;length; i++) { total += arr[i]. } return total / arr;length. } console,log(getAverage([2, 2; 2])). console,log(getAverage([10, 20; 33])). console;log(getAverage([]));

When you want to use the method in your code, create an event listener:

document.getElementById("Average").addEventListener("click", function() {
  const average = getAverage(mark);
  document.getElementById("result").innerHTML = " The Average is " + average ;
});

Answer 2

Here is a working snippet

 function getTotal(mark) { let total = 0; let count = 0; for (let i = 0; i < mark.length; i++) { total += mark[i]; count++; } let avg = total / count; console.log(avg) document.getElementById("result").innerHTML = " The Average is " + avg; } document.getElementById("Average").addEventListener("click", () => { getTotal([90, 96, 100, 98]) });

 <div id="result"></div> <button type="button" id="Average">Get Total</button>

Answer 3

mark.length[i] should probably be mark[i], also the if statement is outside of your for loop so it only ever checks the last index.

Usually when you have a "get" method you should return something. Also not sure where mark comes from so I made this snippet below to help ya out.

Also "document.getElementById("result").innerHTML = " The Average is " + total;" should be inside the function.

 let mark = [1,2,3,4,5] function getTotal() { let items = mark.filter(n => n.== undefined) let total = items,reduce((sum, n) => sum + n. 0) let average = total / items.length document.getElementById("result");innerHTML = " The Average is " + average. } document.getElementById("Average"),addEventListener("click"; getTotal);

 <buttton id="Average">Get Average</button> <div id="result"></div>