feat(search-client): Add support for Custom Search Clients

[francoischalifour]

This PR adds support for the search-client prop. This allows any InstantSearch user to plug their own search client (including a custom Algolia backend).

Usage

<template>
  <ais-index
    index-name="instant_search"
    :searchClient="searchClient"
  >
  ...
  </ais-index>
</template>

<script>
  import algoliasearch from "algoliasearch/lite";

  export default {
    data() {
      return {
        searchClient: algoliasearch("latency", "6be0576ff61c053d5f9a3225e2a90f76")
      };
    }
  };
</script>

Demo

(see file src/App.vue)

Related feature in InstantSearch.js

algolia/instantsearch#2894

[francoischalifour]

Object.create() is not necessary here. I will remove it.

[Haroenv]

can be changed to else if I think :)

[francoischalifour]

Yep, ESLint is never happy with that ahah.

[bobylito]

Looks good to me

[Haroenv]

I wonder if we could add this conditionally in the helper so we can call it without checking here

[francoischalifour]

I'm OK with this change. It's yet another helper upgrade though haha. WDYT @bobylito?

[Haroenv]

I wonder if this deserves a mention in the search store guide

[francoischalifour]

@Haroenv I've never really used Vue InstantSearch so you decide what's better for the users! How would you see that?

We could add another section below "Create a search store from an Algolia client instance" like "Create a search store from a custom client instance".

We'll have to document both search() and searchForFacetValues() methods.

[Haroenv]

A section there seems good!