@guj/rif-js/README.md

Simplify filter,map and such when their use should be conditionnal

# Rif.js

Rif is a "simple" lib with a "simple" syntax meant to simplify certain operations.

## contains (as of today) :

`filterIf` ; `mapIf` ; `concatIf` ; `sliceIf`

## TL;DR
Turn :
```js
myArray
    .filter(elem => {
        if(aCondition){
           return true;
        }
        return checkSomethingOnElement(elem);
    })
    .forEach(doSomethingToElement);
```
Into:
```js
Rif.of(myArray)
    .filterIf(aCondition)(checkSomethingOnElement)
    .forEach(doSomethingToElement);
```

## An example from the everyday life
### State of the art :

Let's say you have a huge bunch of kids but just lost your job, the most reasonable thing to do would be to [sell them all for pharmaceutical research](https://www.youtube.com/watch?v=bzVHjg3AqIQ 'Catholics views on birth control as, satirically, depicted by the Monthy Pythons in their movie: "The meaning of life" which I, most sincerely, recommend you to watch ASAP If you had not yet.') wouldn't it ?

Now, let's assume that you plan this using JS (and why not) this might look like this:
```js
arrayOfKids.forEach(sendToLab); // Haaa ... so nice and concise :D
```
But, suddenly, you receive a call for a part-time job, your new salary (quite conveniently for my point) allows you to provide (exactly) for you, your life-partner and those of your kids that haven't been naughty.

This may end up looking like this:
```js
arrayOfKids
    .filter(isThisKidNaughty)
    .forEach(sendToLab);
/* That, actually, is still pretty nice */
```

Then you remember that:
 - given your lack of access to planned parenthood
   - you're bound to have too many kids again
 - given the current economy/state of the labor-protection
   - you're bound to loose thy job again

So you prepare the code so that it works every time :
```js
arrayOfKids
    .filter(kid => isThisKidNaughty(kid)||!iHaveEnoughIncomeToKeepNiceKids) // ewww !
    .forEach(sendToLab);
```
That's a oneliner but that is not "first glance" clear to everyone so you try to make it more expressive:
```js
arrayOfKids
    .filter(kid => {
        if(!iHaveEnoughIncomeToKeepNiceKids){
            return true;
        }
        return isThisKidNaughty(kid);
    })
    .forEach(sendToLab);
```
Not that much better.

### Now with Rif :
```js
Rif.of(arrayOfKids)
    .filterIf(!iHaveEnoughIncomeToKeepNiceKids)(isThisKidNaughty)
    .forEach(sendToLab);
```

## Bonus :
Rif.js is dynamically built so any addition to `Array.prototype` in the future will be "If-ed" automatically.
For example, if tomorrow, you have a method `respectfulReverse()` that would be like `reverse` but instead of modifying the original, it returns a new array, that method will have it's if without changing code or lib version.

## Other Bonus :
I have some ideas about things I could do next but am too lazy to put up a roadmap. And if YOU have an idea, put an issue or (even better) a PR.

## Remarkable feedbacks :

> That's brilliant ! I wish I'd have had that years ago.
>
> -- <cite>me</cite>