Allow to use functions instead of strings for keys specification

[Phyks]

Hi,

When using Immutable.JS, one has to convert back and forth between Immutable objects and JavaScript objects, to pass them to Fuse.

If we could use functions to specify which key to use, it would allow the use of non-array objects such as Immutable ones:

var books = Immutable.fromJS([{
  title: "Old Man's War"
  author: {
    firstName: "John",
    lastName: "Scalzi"
  }
}]);

var fuse = new Fuse(books, { keys: [item -> item.title, item -> item.getIn(["author", "firstName"])] });

Thanks

[krisk]

@Phyks, in your example you're passing in books into the Fuse instance, however, the first argument is required to be an array, and not an object. This is because it needs to be properly iterated on. I'm all for being able to use functions as key accessors, but the list must remain an array.

[Phyks]

Hmm, books should be an Immutable List of Immutable Map. Immutable List is indeed an object, but is the Immutable equivalent of Array I think?

[krisk]

By doing var books = Immutable.fromJS([...]), books is now not an Array:

var books = Immutable.fromJS([{
  title: "Old Man's War"
  author: {
    firstName: "John",
    lastName: "Scalzi"
  }
}])
Object.prototype.toString.call(books) // [object Object]

vs:

var books = [{
  title: "Old Man's War"
  author: {
    firstName: "John",
    lastName: "Scalzi"
  }
}]
Object.prototype.toString.call(books) // [object Array]

As a result, Fuse.js cannot iterate on that 😢 .

[Phyks]

forEach is implemented in Immutable.List, so replacing looping by functional forEach would make the code work for both Array and Immutable.List I think. https://facebook.github.io/immutable-js/docs/#/List/forEach

[krisk]

I'm merely saying that Fuse.js should not (arguably) be making that decision 😄 .

Note the following:

• forEach is not supported in all platforms
• length is not a property of Immutable.List. Instead, we'd have to use the count() function. Which, again, is "Immutable" specific.

This is why the object being passed in should be an [object Array], and not an Array-like object.

[Phyks]

Ok. I got your point. So being able to support Immutable objects directly in Fuse would add to Immutable-specific code and it would be better to convert back to JS Arrays and pass them?

[krisk]

@Phyks, exactly 😄