Javascript Sum and Average of Array strange issue

Question

Hey guys i have this weird issue with a javascript array that i want to calculate the sum and average of it.

So i have a prompt with an input and i'm asking the users to enter some numbers.

var sums = false;
var numbersArray = [];

function calculateAverage() {
  while (sums == false) {
    var numbers = prompt("Enter Integers.", "");
    if (numbers != null) {
      console.log(numbers);
      numbersArray.push(numbers);


    } else {
      var sum = 0;
      console.log(numbersArray);
      for (var i = 0; i < numbersArray.length; i++) {
        sum += numbersArray[i];
      }

      var avg = sum / numbersArray.length;
      console.log(avg);
      sums = true;
    }
  }
}

 calculateAverage();

So from console logs i get the following prints

4
5
1
["4", "5", "1"]
150.33333333333334

How can this be possible?

Ok my bad! Gonna accept the first answer though cause you are all correct !

A concise way of getting the average of an array in JS is avg = ["4", "5", "1"].reduce((p,c,_,a) => p + c/a.length,0); — Redu
– Redu, Commented Dec 19, 2016 at 15:48

Deep · Accepted Answer · 2016-12-19 13:09:00Z

3

Convert string to integer before pushing into the Array

Use parsInt

numbersArray.push(parseInt(numbers));

var sums = false;
var numbersArray = [];

function calculateAverage() {
  while (sums == false) {
    var numbers = prompt("Enter Integers.", "");
    if (numbers != null) {
      console.log(numbers);
      numbersArray.push(parseInt(numbers));


    } else {
      var sum = 0;
      console.log(numbersArray);
      for (var i = 0; i < numbersArray.length; i++) {
        sum += numbersArray[i];
      }

      var avg = sum / numbersArray.length;
      console.log(avg);
      sums = true;
    }
  }
}

calculateAverage();

answered Dec 19, 2016 at 13:09

Deep

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Comments

Viplock · Accepted Answer · 2016-12-19 13:16:29Z

3

Just do parseInt before adding

var sums = false;
var numbersArray = [];

function calculateAverage() {
  while (sums == false) {
    var numbers = prompt("Enter Integers.", "");
    if (numbers != null) {
      console.log(numbers);
      numbersArray.push(numbers);


    } else {
      var sum = 0;
      console.log(numbersArray);
      for (var i = 0; i < numbersArray.length; i++) {
        sum += parseInt(numbersArray[i]);
      }

      var avg = sum / numbersArray.length;
      console.log(avg);
      sums = true;
    }
  }
}

 calculateAverage();

edited Dec 19, 2016 at 13:16

answered Dec 19, 2016 at 13:11

Viplock

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Comments

FCin · Accepted Answer · 2016-12-19 13:09:17Z

2

sum += numbersArray[i];

It should be

sum += parseInt(numbersArray[i]);

Because without it you add another char to your string.

answered Dec 19, 2016 at 13:09

FCin

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Comments

Azad · Accepted Answer · 2016-12-19 13:09:41Z

2

convert the user entered variable to integer before push into array

numbersArray.push(+ numbers);

answered Dec 19, 2016 at 13:09

Azad

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Comments

Nitheesh · Accepted Answer · 2016-12-19 13:12:29Z

Use parseFloat or parseInt method to convert string to nuber before adding. Please find the attached code.

<!DOCTYPE html>
<html>

<script>
    var sums = false;
    var numbersArray = [];

    function calculateAverage() {
        while (sums == false) {
            var numbers = prompt("Enter Integers.", "");
            if (numbers != null) {
                console.log(numbers);
                numbersArray.push(numbers);


            } else {
                var sum = 0;
                console.log(numbersArray);
                for (var i = 0; i < numbersArray.length; i++) {
                    sum += parseFloat(numbersArray[i]);
                }

                var avg = sum / numbersArray.length;
                console.log(avg);
                sums = true;
            }
        }
    }
    calculateAverage();
</script>

<body>
</body>

</html>

vijay · Accepted Answer · 2016-12-19 13:12:54Z

2

You need to add parseInt to sum the integers otherwise 4,5,1 will joined to form 451 and average 451/3 = 150.33333

var sums = false;
var numbersArray = [];

function calculateAverage() {
  while (sums == false) {
    var numbers = prompt("Enter Integers.", "");
    if (numbers != null) {
      console.log(numbers);
      numbersArray.push(numbers);


    } else {
      var sum = 0;
      console.log(numbersArray);
      for (var i = 0; i < numbersArray.length; i++) {
        sum += parseInt(numbersArray[i]);
      }

      var avg = sum / numbersArray.length;
      console.log(avg);
      sums = true;
    }
  }
}
window.onload = calculateAverage();

answered Dec 19, 2016 at 13:12

vijay

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Comments

Sankar · Accepted Answer · 2016-12-19 13:14:03Z

2

Need to use ParseInt()

var sums = false;
var numbersArray = [];
calculateAverage();

function calculateAverage() {
  while (sums == false) {
    var numbers = prompt("Enter Integers.", "");
    if (numbers != null) {
      console.log(numbers);
      numbersArray.push(numbers);


    } else {
      var sum = 0;
      console.log(numbersArray, numbersArray.length);
      for (var i = 0; i < numbersArray.length; i++) {
        sum += parseInt(numbersArray[i]);

      }
      console.log(sum);
      var avg = sum / numbersArray.length;
      console.log(avg);
      sums = true;
    }
  }
}

answered Dec 19, 2016 at 13:14

Sankar

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Comments

Rajshekar Reddy · Accepted Answer · 2016-12-19 13:16:21Z

2

How can this be possible?

Right now you are dealing with array of strings hence the behavior.

Convert the string into numeric values and this should be fixed. To change string to numeric use parseInt()

numbersArray.push(parseInt(numbers,10));

edited Dec 19, 2016 at 13:16

answered Dec 19, 2016 at 13:10

Rajshekar Reddy

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Comments

Bugs Bunny · Accepted Answer · 2020-10-06 12:44:07Z

0

I see that you've found a solution already, but I've been using an easier package called Shortcuts. You can use const short = require('@testgrandma/shortcuts'); to install it and then for this script you can do

short.arrayave([array]);

It'll return you the average of the array.

https://www.npmjs.com/package/@testgrandma/shortcuts

answered Oct 6, 2020 at 12:44

Bugs Bunny

576 bronze badges

2 Comments

fluidguid Over a year ago

Question does not talk about npm. Mostly your answer is a comment, not an answer.

Bugs Bunny Over a year ago

It's an NPM package that I think is easier to use to find averages and other useful functions.

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