Add scrollto parameters (#4)

* Fix issue #3
* Some improvements
* Readme updated

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@wide/scroll",
-  "version": "2.1.0",
+  "version": "2.1.1",
   "description": "Observe scroll progression and provides helpers for parallax, locking and sticky effects.",
   "license": "MIT",
   "author": "Aymeric Assier (https://github.com/myeti)",

readme.md

@@ -79,6 +79,41 @@ import { JUMP_CONFIG } from '@wide/scroll'
 JUMP_CONFIG.offset = -20 // top offset for all jump
 ```
 
+You can aslo define config locally by adding HTML attributes:
+```html
+<button
+  data-scrollto="#footer"
+  data-scrollto.duration="1010"
+  data-scrollto.offset="0"
+  data-scrollto.a11y="false"
+  data-scrollto.callback="scrollToCallback"
+  data-scrollto.easing="scrollToEasing"
+>
+  Scroll to footer
+</button>
+```
+```js
+window.scrollToCallback = () => {
+  // Do some stuffs when scroll has been completed
+}
+
+window.scrollToEasing = () => {
+  // My custom easing animation code
+}
+```
+
+> Note: Those parameters will override default (global) parameters.
+
+### Parameters
+| Name | Type | Description | Default value |
+|---|---|---|---|
+| `duration` | `number` | Pass the time the `scrollto()` takes, in milliseconds. | `800` |
+| `offset` | `number` | Offset a `scrollto()`, only if to an element, by a number of pixels. | `-80` |
+| `a11y` | `boolean` | If enabled, and scrolling to an element: add a tabindex to, and focus the element | `true` |
+| `callback` | `function` | Pass a function that will be called after the `scrollto()` has been completed. | `null` |
+| `easing` | `function` | Easing function used to transition the `scrollto()`. | `null` |
+
+More informations on [`Jump.js` documentation](https://github.com/callmecavs/jump.js#options).
 
 ## Locker
 
@@ -138,7 +173,6 @@ const el = document.querySelector('.something')
 parallax(el, { speed: .4 })
 ```
 
-
 ## Sticky
 
 Internally use [`stickybits`](https://www.npmjs.com/package/stickybits) library.

src/index.js

@@ -4,22 +4,59 @@ import jump from 'jump.js'
 import uos from 'uos'
 
 
+/**
+ * Data attribute keyword
+ * @type {string}
+ */
+const dataKeyword = 'scrollto'
+
+
+/**
+ * Data attribute option separator
+ * @type {string}
+ */
+const dataSeparator = '.'
+
+
 /**
  * Jump default config
  * @type {Object}
+ * 
+ * @tutorial https://github.com/callmecavs/jump.js/blob/master/src/jump.js#L88
  */
-export let JUMP_CONFIG = {
+export const JUMP_CONFIG = {
   duration: 800,
   offset: -80,
-  a11y: true
+  a11y: true,
+  callback: null, // Global function
+  easing: null // Global function
+}
+
+
+/**
+ * Jump config variables type
+ * @type {Object}
+ * 
+ * @tutorial https://github.com/callmecavs/jump.js/blob/master/src/jump.js#L88
+ */
+export const JUMP_CONFIG_TYPE = {
+  duration: 'number',
+  offset: 'number',
+  a11y: 'boolean',
+  callback: 'function',
+  easing: 'function'
 }
 
 
 /**
  * Observe element [data-scrollto] in DOM to add effect
  */
-observe('[data-scrollto]', {
-  bind: el => el.addEventListener('click', e => to(e.dataset.scrollto))
+observe(`[data-${dataKeyword}]`, {
+  bind: el => el.addEventListener('click', () => {
+    if (el.dataset[dataKeyword]) {
+      scrollTo(document.querySelector(el.dataset.scrollto), getOptions(el.dataset))
+    }
+  })
 })
 
 
@@ -29,8 +66,78 @@ observe('[data-scrollto]', {
  * @param {Object} options 
  */
 export function scrollTo(target, options = {}) {
-  const opts = Object.assign({}, JUMP_CONFIG, options)
-  jump(target, opts)
+  if (target) {
+    const opts = Object.assign({}, JUMP_CONFIG, options)
+    jump(target, opts)
+  }
+}
+
+
+/**
+ * Get options from dataset
+ * @param {DOMStringMap} dataset 
+ * @return {Object} Jump options
+ */
+function getOptions(dataset) {
+  const options = {}
+
+  if (dataset && typeof dataset === 'object') {
+    for (const [dataName, dataValue] of Object.entries(dataset)) {
+      const optionName = getOptionName(dataName)
+
+      if (optionName) {
+        const optionValue = getOptionValue(optionName, dataValue)
+
+        if (optionValue !== null) {
+          options[optionName] = optionValue
+        }
+      }
+    }
+  }
+
+  return options
+}
+
+
+/**
+ * Get option name from dataset name
+ * @param {string} dataName 
+ * @return {string|null} Jump option name
+ */
+function getOptionName(dataName) {
+  const dataKeywordSeparator = dataKeyword + dataSeparator
+
+  // If an option is setted...
+  if (dataName.startsWith(dataKeywordSeparator)) {
+    const dataOptionName = dataName.slice(dataKeywordSeparator.length)
+
+    // ...and exists in jump.js, add it
+    return Object.hasOwn(JUMP_CONFIG, dataOptionName) ? dataOptionName : ''
+  }
+
+  return null
+}
+
+
+/**
+ * Get option value from dataset string value
+ * @param {string} optionName 
+ * @param {string} optionValue 
+ * @return {any} Value formatted
+ */
+function getOptionValue(optionName, optionValue) {
+  if (!optionName) return null
+
+  switch (JUMP_CONFIG_TYPE[optionName]) {
+    case 'boolean':
+      return optionValue === 'true'
+    case 'function':
+      return window[optionValue] || null
+    case 'number':
+      return optionValue * 1
+    default:
+      return optionValue
+  }
 }