Javascript 平均和

Question

Working on a form with two input fields for a user to input the names and marks of their students, along with four buttons, one adds the name & mark which stores each value in the console. The second displays the stored results in a display box, the third button is a clear all which clears the console and the display box.

The fourth button is to calculate the average of the inputted marks. My problem is that these marks are not stored in the array below, they are stored in the console from the users input. I am trying to take these values stored in the console and work out the average.

<form onsubmit="return false">
    <h4>Enter student results</h4>

    Name:
    <input type="text" id="name" autofocus required>

    Mark:
    <input type="number" id="mark" min="0" max="100" required>




    <div id="buttonBlock">
        <input type="button" id="Add" value="Add Result">
        <input type="button" id="Clear" value="Clear All">
        <input type="button" id="Display" value="Display All">
        <input type="button" id="Average" value="Calculate Average">
    </div>


</form>

<p id="result"></p>

let insertName = [];
let insertMark = [];
 //Arrays//

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

Can't see source of mark to see if they are actually numbers. You may need to parse to integer. Didn't notice your intention. @Niels saw it.

 mark = [1,2,3,4,5,6] function getTotal() { let total = 0; let count = 0; //let i = 0; // someone edited this to fix poor style for (let i = 0; i < 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);

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

Created a fully working demo. But honestly for a small hack like this with a few typos, all he really needed was to have it quickly pointed out where he made mistakes.

Answer 2

You declared i twice

let i = 0;

for (let i = 0; i < mark.length; i++)

This code never executed, since your mark.length is 0

total += mark[i]; 

And this code is also not executed, because mark[0] is undefined

count++;
total += mark[i];

Tge avg = 0/0 which is NaN, but total is still 0