Javascript Average Array

Question

this is my first post. I am writing a program to get input from four input boxes, find out the sum of these four and finding the average. When i do so I get a NaN error, can someone point where I am going wrong. Thanks ``` Average marks

Accepted Answer

Welcome to Stackoverflow :) We would be glad to help you while learning our tools better. Just one note about the algorithm: move the average calculation command outside the loop:

```
for(var x = 0; x < scores.length; x ++)
{
  Sum = Sum + scores[x];  //or Sum += scores[x];
}

average = Sum / scores.length;  //length of the array scores is in scores.length
```

I would use `parseInt()` instead of `new Number()` because `new Number()` creates an object while `parseInt()` gives you the actual literal value as a result. (better performance).

By the way, don't forget to put `var` before every variable definition unless you want them to be accessed globaly (bad idea). You did a good job with all variables except `scores`. The definition should be `var scores` though that is not the source of this error.

Another point: you can check if the result of `parseInt()` using `isNaN()` function. If your numbers can have decimal points, you can use `parseFloat()` also:

parseInt()

parseFloat()

The result of both functions is NaN (not a number) if the conversion from string to number fails.

And finally, I think it is a good idea that you defined the array with a specified length. It improves the readability of your code. However it is not necessary in Javascript as it automatically increases/decreases the length of the array at runtime so you don't have to decide in advance how long it should be. It can be a good thing or a bad thing depending how you use it. But in general you can use `var myarr=[];` instead of `var myarr= new Array();`. However when you want to hint the other developers what's going on, you may specify the array length as well: `var myarr=new Array(4);`.

And final point for using Stackoverflow: please accept the best answer and "up vote" the other useful answers. This way you will get a score and other people as well.

Good luck

Javascript Average Array

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