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+# DropLab
+
+A generic dropdown for all of your custom dropdown needs.
+
+## Usage
+
+DropLab can be used by simply adding a `data-dropdown-trigger` HTML attribute.
+This attribute allows us to find the "trigger" _(toggle)_ for the dropdown,
+whether that is a button, link or input.
+
+The value of the `data-dropdown-trigger` should be a CSS selector that
+DropLab can use to find the trigger's dropdown list.
+
+You should also add the `data-dropdown` attribute to declare the dropdown list.
+The value is irrelevant.
+
+The DropLab class has no side effects, so you must always call `.init` when
+the DOM is ready. `DropLab.prototype.init` takes the same arguments as `DropLab.prototype.addHook`.
+If you do not provide any arguments, it will globally query and instantiate all droplab compatible dropdowns.
+
+```html
+<a href="#" data-dropdown-trigger="#list">Toggle</a>
+
+<ul id="list" data-dropdown>
+  <!-- ... -->
+<ul>
+```
+```js
+const droplab = new DropLab();
+droplab.init();
+```
+
+As you can see, we have a "Toggle" link, that is declared as a trigger.
+It provides a selector to find the dropdown list it should control.
+
+### Static data
+
+You can add static list items.
+
+```html
+<a href="#" data-dropdown-trigger="#list">Toggle</a>
+
+<ul id="list" data-dropdown>
+  <li>Static value 1</li>
+  <li>Static value 2</li>
+<ul>
+```
+```js
+const droplab = new DropLab();
+droplab.init();
+```
+
+### Explicit instantiation
+
+You can pass the trigger and list elements as constructor arguments to return
+a non-global instance of DropLab using the `DropLab.prototype.init` method.
+
+```html
+<a href="#" id="trigger" data-dropdown-trigger="#list">Toggle</a>
+
+<ul id="list" data-dropdown>
+  <!-- ... -->
+<ul>
+```
+```js
+const trigger = document.getElementById('trigger');
+const list = document.getElementById('list');
+
+const droplab = new DropLab();
+droplab.init(trigger, list);
+```
+
+You can also add hooks to an existing DropLab instance using `DropLab.prototype.addHook`.
+
+```html
+<a href="#" data-dropdown-trigger="#auto-dropdown">Toggle</a>
+<ul id="auto-dropdown" data-dropdown><!-- ... --><ul>
+
+<a href="#" id="trigger" data-dropdown-trigger="#list">Toggle</a>
+<ul id="list" data-dropdown><!-- ... --><ul>
+```
+```js
+const droplab = new DropLab();
+
+droplab.init();
+
+const trigger = document.getElementById('trigger');
+const list = document.getElementById('list');
+
+droplab.addHook(trigger, list);
+```
+
+
+### Dynamic data
+
+Adding `data-dynamic` to your dropdown element will enable dynamic list rendering.
+
+You can template a list item using the keys of the data object provided.
+Use the handlebars syntax `{{ value }}` to HTML escape the value.
+Use the `<%= value %>` syntax to simply interpolate the value.
+Use the `<%= value %>` syntax to evaluate the value.
+
+Passing an array of objects to `DropLab.prototype.addData` will render that data
+for all `data-dynamic` dropdown lists tracked by that DropLab instance.
+
+```html
+<a href="#" data-dropdown-trigger="#list">Toggle</a>
+
+<ul id="list" data-dropdown data-dynamic>
+  <li><a href="#" data-id="{{id}}">{{text}}</a></li>
+</ul>
+```
+```js
+const droplab = new DropLab();
+
+droplab.init().addData([{
+  id: 0,
+  text: 'Jacob',
+}, {
+  id: 1,
+  text: 'Jeff',
+}]);
+```
+
+Alternatively, you can specify a specific dropdown to add this data to but passing
+the data as the second argument and and the `id` of the trigger element as the first argument.
+
+```html
+<a href="#" data-dropdown-trigger="#list" id="trigger">Toggle</a>
+
+<ul id="list" data-dropdown data-dynamic>
+  <li><a href="#" data-id="{{id}}">{{text}}</a></li>
+</ul>
+```
+```js
+const droplab = new DropLab();
+
+droplab.init().addData('trigger', [{
+  id: 0,
+  text: 'Jacob',
+}, {
+  id: 1,
+  text: 'Jeff',
+}]);
+```
+
+This allows you to mix static and dynamic content with ease, even with one trigger.
+
+Note the use of scoping regarding the `data-dropdown` attribute to capture both
+dropdown lists, one of which is dynamic.
+
+```html
+<input id="trigger" data-dropdown-trigger="#list">
+<div id="list" data-dropdown>
+  <ul>
+    <li><a href="#">Static item 1</a></li>
+    <li><a href="#">Static item 2</a></li>
+  </ul>
+  <ul data-dynamic>
+    <li><a href="#" data-id="{{id}}">{{text}}</a></li>
+  </ul>
+</div>
+```
+```js
+const droplab = new DropLab();
+
+droplab.init().addData('trigger', [{
+  id: 0,
+  text: 'Jacob',
+}, {
+  id: 1,
+  text: 'Jeff',
+}]);
+```
+
+## Internal selectors
+
+DropLab adds some CSS classes to help lower the barrier to integration.
+
+For example,
+
+* The `droplab-item-selected` css class is added to items that have been selected
+either by a mouse click or by enter key selection.
+* The `droplab-item-active` css class is added to items that have been selected
+using arrow key navigation.
+* You can add the `droplab-item-ignore` css class to any item that you do not want to be selectable. For example,
+an `<li class="divider"></li>` list divider element that should not be interactive.
+
+## Internal events
+
+DropLab uses some custom events to help lower the barrier to integration.
+
+For example,
+
+* The `click.dl` event is fired when an `li` list item has been clicked. It is also
+fired when a list item has been selected with the keyboard. It is also fired when a
+`HookButton` button is clicked (a registered `button` tag or `a` tag trigger).
+* The `input.dl` event is fired when a `HookInput` (a registered `input` tag trigger) triggers an `input` event.
+* The `mousedown.dl` event is fired when a `HookInput` triggers a `mousedown` event.
+* The `keyup.dl` event is fired when a `HookInput` triggers a `keyup` event.
+* The `keydown.dl` event is fired when a `HookInput` triggers a `keydown` event.
+
+These custom events add a `detail` object to the vanilla `Event` object that provides some potentially useful data.
+
+## Plugins
+
+Plugins are objects that are registered to be executed when a hook is added (when a droplab trigger and dropdown are instantiated).
+
+If no modules API is detected, the library will fall back as it does with `window.DropLab` and will add `window.DropLab.plugins.PluginName`.
+
+### Usage
+
+To use plugins, you can pass them in an array as the third argument of `DropLab.prototype.init` or `DropLab.prototype.addHook`.
+Some plugins require configuration values, the config object can be passed as the fourth argument.
+
+```html
+<a href="#" id="trigger" data-dropdown-trigger="#list">Toggle</a>
+<ul id="list" data-dropdown><!-- ... --><ul>
+```
+```js
+const droplab = new DropLab();
+
+const trigger = document.getElementById('trigger');
+const list = document.getElementById('list');
+
+droplab.init(trigger, list, [droplabAjax], {
+  droplabAjax: {
+    endpoint: '/some-endpoint',
+    method: 'setData',
+  },
+});
+```
+
+### Documentation
+
+* [Ajax plugin](plugins/ajax.md)
+* [Filter plugin](plugins/filter.md)
+* [InputSetter plugin](plugins/input_setter.md)
+
+### Development
+
+When plugins are initialised for a droplab trigger+dropdown, DropLab will
+call the plugins `init` function, so this must be implemented in the plugin.
+
+```js
+class MyPlugin {
+  static init() {
+    this.someProp = 'someProp';
+    this.someMethod();
+  }
+
+  static someMethod() {
+    this.otherProp = 'otherProp';
+  }
+}
+
+export default MyPlugin;
+```