Add prefer-array-find rule

[fisker]

Fixes #730

[sindresorhus]

The rule should be named prefer-array-find.

[fisker]

I thought about this rule name too, I agree it should be prefer-array-find, and I even want rename no-reduce to no-array-reduce, then I realize that rule already published in v20.

[fisker]

function foo([bar] = array.filter(baz)) {}

This can't fix, right?

[fisker]

I'm going to add suggestion to

const [foo = bar] = array.filter(fn);

Suggestion 1:

const foo = array.find(fn) || bar;

Suggestion 2:

const foo = array.find(fn) ?? bar;

God, I thought this is simple, so I started it.

[fisker]

Following cases not handled.

const foo = array.filter(fn);
const bar = foo.shift();

I didn't handle this, because .shift() has side effect, we should know it's only called once, and not in a function/while/for.

const foo = array.filter(fn);
while (foo.shift()) {}

---

const foo = array.filter(fn);
const [bar] = foo;

I didn't handle this, because we need handle/exclude this

const foo = array.filter(fn);
const [bar = baz] = foo;

I use suggestion for const [foo = baz] = array.filter(fn);, but we can't use suggestion for this. because we are reportting problem on .filter, suggest to use ?? or || will be weird, we need decide ignore this case or do something different.

---

let bar;
const foo = array.filter(fn);
[bar] = foo;

Same as second one.

let bar;
const foo = array.filter(fn);
[bar = baz] = foo;

[sindresorhus]

function foo([bar] = array.filter(baz)) {}
This can't fix, right?

No point in handling that. I have never seen such code in practice.

[fisker]

@oscarmarcelo Can you help review this?

[oscarmarcelo]

Well, I'm not yet that familiar with the intricacies of unicorn, but for what I've seen here, this looks pretty solid! Congratulations and thank you, @fisker! 👏

[sindresorhus]

Nice work as always, @fisker 👍