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Namespaced Attributes

by @leastbad leastbad

Good

<!-- index.html -->
<input data-controller="filter" data-filter-param-category="cats" data-filter-param-rating="5" data-filter-param-color="black" type="text" data-action="input->filter#update">
// filter_controller.js
import { Controller } from "stimulus";

export default class extends Controller {
  update () {
    const url = new URL(window.location)
    Object.keys(Object.assign({}, this.element.dataset))
      .filter(attr => attr.startsWith("filterParam"))
      .forEach(attr => {
        url.searchParams.set(
          attr.slice(11).replace(/^\w/, c => c.toLowerCase()),
          this.element.dataset[attr]
        )
      })
    history.pushState({}, '', url.toString())
  }
}

Rationale

Building on the Configurable Controllers example, we might want to work with an arbitrary set of attributes that are namespace not just to the controller but identified as parameters.

Unfortunately, Stimulus doesn’t make it easy to obtain a list of available attributes, or specify further namespace criteria. Bypassing the Stimulus data accessor entirely, we first convert the controller element’s dataset to a JS object before emitting an array of its’ keys. We retain only the attributes named data-filter-param-* and then strip those attributes down to their base names for inclusion in the URL querystring.

Note: you’ll need to adjust the value passed to slice to account for the length of your controller’s identifier.

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