# Better debug your code with console.timer()

Hello good people! In this article, I want to shed light on a very interesting console function. It's called `console.timer()` and might help you understand how your code runs and optimize it.

This will be a rather short article. We'll go through two simple examples to understand how it works and hopefully get you started.

## How `console.timer()` works ⌚

Let's get straight to the point with a simple code snippet. We'll declare an array and fill it with some values as below.

```javascript
console.time('mylabel');

let arr = [];

for (let i = 0; i < 100000; i++) {
  arr[i] = (i + 1) * 100;
}

console.timeEnd('mylabel');
```

As you can see, I've surrounded the snippet with `console.time('label')` and `console.timeEnd('mylabel')`. Running this on NodeJS or your browser's console will output a line as follows :

```
mylabel: 4.125 ms
```

![image.png](https://cdn.hashnode.com/res/hashnode/image/upload/v1620347752054/EgDfhlxPk.png)

*So what happened?* 🧐

Imagine you have a stopwatch, you'll tap the **start** button once it reaches the `console.time()` and you'll tap the **stop** button once it reaches the `console.timeEnd()`. This exactly what the JavaScript runtime is doing, just instead of you fiddling with a stopwatch it does it for you 😁 !

The `mylabel` is just a way to help us use *"multiple stopwatches"*. Your label needs to match a start and an end to work properly so be mindful about that.

## Multiple timings with `console.timeLog()` ⏳

Let's make our example more interesting with another for loop and try to use `console.timeLog()` with it:

```javascript
console.time('mylabel');

let arr = [];

for (let i = 0; i < 100000; i++) {
  arr[i] = (i + 1) * 100;
}

console.timeLog('mylabel');

let arr2 = [];

for (let i = 0; i < 100000; i++) {
    arr2.push((arr[i] * Math.PI) / 1.33);
}

console.timeEnd('mylabel');
```

If you run again this code, you'll have an input roughly like the following:

```
mylabel: 4.179ms
mylabel: 11.824ms
```

As you can see, now we have an intermediary output. This is awesome because you can use the **same label** to keep track of the timings of each block of code as you like.

## Wrap-up 📦

And that's it! Using `console.time()` is really straightforward. I used it two days ago to find out which loop was taking too much time to run and thus impact our client's app performance.

I really hope you like this shorter format. In any case, I'll be pleased to read your feedback.

Cheers!

Photo by [@jontyson](https://unsplash.com/@jontyson) from [Unsplash.com](https://unsplash.com/).