# Public Solving: Checking the sleighs automatically

The elves build and try a lot of different sleighs for Santa. Because of the number of sleighs, they are looking for an automated report.

[Click here to view the original puzzle](https://github.com/devadvent/puzzle-20).

Each sleigh is already being tested, so they have the data available.
It's up to us to check if each system check is passing. If so, we should return a specific letter.

The checks pass if a value is above 90%.
The result should be an alphabetically sorted string.

If all checks fail, we should return an `X`.

## Creating the sleigh system check

I won't describe the solution for this one but rather walk you straight through my implementation.

The sleigh has multiple attributes, but they are not sorted.
So I decided to start with a `checkMap` object.
This object will keep all the checks in alphabetical order and contain their letter value.

```js
const checkMap = {
  accelerometer: 'A',
  breaks: 'B',
  compass: 'C',
  gyroscope: 'G',
  humiditySensor: 'H',
  langdingSuspension: 'L',
  navigation: 'N',
  pressureSensor: 'P',
  temperatureSensor: 'T',
  windSensor: 'W',
};
```

I want to loop over these checks and add a letter if the value passes the inspection.

Once again, I'll be using the [`reduce` method](https://daily-dev-tips.com/posts/javascript-reduce-method/).

We have to extract the object keys so we can loop over them.

```js
const checks = Object.keys(checkMap).reduce((output, check) => {
 // Do check
}, '');
```

The check is actually the easy part as a value is valid if over 90%.

If that is the case, I add a letter to the output array.

```js
const checks = Object.keys(checkMap).reduce((output, check) => {
	if (sleigh[check] >= 0.9) {
	  output += checkMap[check];
	}
	return output;
}, '');
```

What happens here is that if the sleighs check for the current check is above `0.9` (90%), we add the letter for that check to our array.

Now we just need a check if this `checks` string is empty.
If so, all checks must have failed, and we should return an `X`.

```js
return checks.length ? checks : 'X';
```

Let's see how we did by running the test.

![Test turning green](https://cdn.hashnode.com/res/hashnode/image/upload/v1640059456655/wJS1ELvOQ.png)

That's it!
We got there, and we can now safely evaluate all the sleighs.

Do let me know what you would do differently in this solution.

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