Create a `isPositive` function that takes a number as
parameter and return true if the given number is
stricly positive, or false otherwise
Create a function named `isPositive` that takes a number as a argument, returning `true` if the number is strictly positive, and `false` otherwise.
Create the `abs` function that takes one number argument
and returns its absolute value.
You are not allowed to use `Math.abs`, make your own.
Create a function named `abs` that takes a number as an argument and returns its absolute value. You must make your own implementation. You **must not** use `Math.abs()`.
Create a `blockChain` that create a block in your very own block chain.
Create a function named `blockChain` that creates a block in your very own block chain. It takes 2 arguments:
the function takes 2 arguments:
- `data` any valid JSON data
- `prev` the previous block, if no block are given it should use the
genesis block: `{ index: 0, hash: '0' }`
- `data`: any valid JSON data.
- `prev`: the previous block, if no block are given it should use the genesis block: `{ index: 0, hash: '0' }`.
A block must have the following properties:
- `index`
- `hash` a computed hash using the concatenation of the `index`, `hash`
and stringified `data` and hashing all of it using the provided `hashCode`.
- `data` the data (not encoded in JSON)
- `prev` the previous block
- `chain` a function that takes a new `data` and create the next block with it.
- `hash`: a computed hash using the `hashCode` function provided. You will need to pass it a concatenation of the block's `index`, the previous block's `hash` and the block's stringified `data`.
- `data`: any valid object.
- `prev`: the previous block.
- `chain`: a function that accepts `data` as an argument, and creates the next block with it.
Someone once said that a dog makes 7 years for each human year.
Someone once said that a human year is equal to 7 dog years.
Create a `dogYears` function that if given a planet name and an age in seconds,
calculates how old a dog would be on the given planet.
Create a function named `dogYears`, that accepts the name of a planet, and the age of the dog in seconds. Your function should return the age of the dog on that planet in dog years.
- `earth`: orbital period 1.0 Earth years, 365.25 Earth days, or 31,557,600 seconds
- `mercury`: orbital period 0.2408467 Earth years
- `venus`: orbital period 0.61519726 Earth years
- `mars`: orbital period 1.8808158 Earth years
- `jupiter`: orbital period 11.862615 Earth years
- `saturn`: orbital period 29.447498 Earth years
- `uranus`: orbital period 84.016846 Earth years
- `neptune`: orbital period 164.79132 Earth years
- `earth`: orbital period 1.0 Earth years, 365.25 Earth days, or 31,557,600 seconds.
- `mercury`: orbital period 0.2408467 Earth years.
- `venus`: orbital period 0.61519726 Earth years.
- `mars`: orbital period 1.8808158 Earth years.
- `jupiter`: orbital period 11.862615 Earth years.
- `saturn`: orbital period 29.447498 Earth years.
- `uranus`: orbital period 84.016846 Earth years.
- `neptune`: orbital period 164.79132 Earth years.
So if you were told someone that their dog were 1,000,000,000 seconds old, you should be able to say that the dog is 221.82 Earth-years old.
If you were told that a dog was 1,000,000,000 seconds old, you should calculate that the dog would be 221.82 Earth-years old.
You will have to format the number so that the result is rounded like the example above.
Hello and welcome to the JS piscine, first you will have to learn
to execute javascript.
Welcome to the JS piscine 👋.
Being a special child, JS can run in different **runtime**, what you can
do with it greatly depend of your runtime.
First you will have to learn to execute JavaScript.
Luckily you don't need to install anything for that since all you
need is a web browser.
JavaScript can run in different **runtime** environments. What you can do with JavaScript will greatly depend on the runtime. Even different web browsers (Chrome, Firefox, Safari etc) count as different runtime environments.
> Main runtime for executing JS are: any web browser, NodeJS and Deno.
We'll start by running JavaScript in your browser, so you don't need to install anything to get started.
Let's make a hello world:
Some common JavaScript runtime environments:
- Web browsers
- [Node.js](https://nodejs.org/)
- [Deno](https://deno.land/)
```bash
# first we create the javascript file
echo "console.log('Hello World')" > how-2-js.js
Let's make a hello world. First we create the JavaScript file
# To run JS in your browser you need to import it from an HTML page:
Now open your browser at the specified port. You'll use an appropriate command for your system:
- Linux: `xdg-open`
- macOS: `open`
- Windows: `start`
```sh
xdg-open 'http://localhost:8000'
```
> `xdg-open` find your default application for the given argument
> on mac it's just `open` and it's `start` on windows
You can now open your web browser console (`ctrl`+`shift`+`i`)
and you should see your hello world.
> The console is a very handy place to test code and explore how the language
> works, don't be shy and play in it !
You can now open your web browser console. From Google Chrome, press **Command+Option+J** (Mac) or **Control+Shift+J** (Windows, Linux, ChromeOS), and you should see your hello world.
Great ! you are all set, if you want to re-execute your script, just refresh.
The console is a handy place to test your code.
You now just have to create a repository named `((ROOT))`,
which will hold all your solutions for this piscine
and just add your 2 generated files to it, we will start slow for now... 🐢
You are all set. If you want to re-execute your script, just refresh.
### Recommendation
Create a repository named `((ROOT))` which will hold all your solutions for this piscine. Add your 2 generated files to it.
Videos designed to give **hints** are assigned to each quest. It is strongly suggested to watch them as you go.
- a `first` function that takes an array or a string
and return the first element.
- `first`: that takes an array or a string and returns its first element or character.
- a `last` function that takes an array or a string
and return the last element.
- `last`: that takes an array or a string and return its last element or character.
- a `kiss` function that returns an array of 2 elements
the last and the first element, in that order
- `kiss`: that takes an array or string, and returns an array of 2 elements. The returned array should contain the last and first elements or characters, in that order.
Create the `sign` function that takes one number argument
and return 1 if the number is positive, -1 if the number is negative
and 0 if the number is exactly 0
You must not just use `Math.sign`, make your own.
Create a function named `sign` that takes one number argument; returning `1` if the number is positive, `-1` if the number is negative and `0` if the number is exactly 0.
> You must not just use `Math.sign`, make your own.
Create the `sameSign` function that takes 2 numbers as arguments and return true
if they both have the same sign, or false otherwise.
Create a function named `sameSign` that takes 2 numbers as arguments and returns `true` if they both have the same sign, or false otherwise.
Dav Hojt
2 years ago
committed by