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src/compositions/readme.md

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+# Compositions
+
+Compositions are reusable snippets of functionality that can be used in Vue components.
+
+## Table of Contents
+
+* [Event Listener](#event-listener)
+* [Window Size](#window-size)
+
+## Event Listener
+
+The event listener composition allows you to bound event listeners to global elements.
+
+**Note:** You should rely on Vue's event handlers like `@click` whenever possible. This composition acts as an escape hatch for triggering things based on out-of-component events.
+
+The composition removes the event handler whenever the component is unmounted.
+
+### Usage
+
+```js
+import { createComponent } from '@vue/composition-api';
+import useEventListener from '@/compositions/event-listener';
+
+export default createComponent({
+	setup() {
+		useEventListener(window, 'scroll', onScroll);
+
+		function onScroll(event) {
+			console.log(event);
+		}
+	}
+});
+```
+
+## Window Size
+
+Returns a `ref` of `width` and `height` of the current window size. Updates the value on window resizes.
+
+### Usage
+
+```js
+import { createComponent } from '@vue/composition-api';
+import useWindowSize from '@/compositions/window-size';
+
+export default createComponent({
+	setup() {
+		const { width, height } = useWindowSize();
+	}
+});
+```