Replace the options parameter by exporting the axeCoreInstance

Author: jul-sh

README.MD

@@ -23,12 +23,9 @@ Important: When adding Agnostic Axe to your project, be sure to only import it i
 
 ## API Details
 
-The `AxeObserver` constructor takes two parameters:
+The `AxeObserver` constructor accepts one parameter:
 
 - `violationsCallback` (required). A function that is invoked with an array of violations, as reported by [axe-core](https://github.com/dequelabs/axe-core). To log violations to the console, simply pass the `logViolations` function exported by this module.
-- `options` (optional). An object with that supports the following configuration keys:
-  - `axeCoreConfiguration` (optional). [A configuration object for axe-core](https://github.com/dequelabs/axe-core/blob/master/doc/API.md#api-name-axeconfigure). Overwrites the default configuration used by agnostic axe.
-  - `axeCoreInstanceCallback` (optional). A callback that is invoked with the [axe-core](https://github.com/dequelabs/axe-core) instance.
 
 The `AxeObserver.observe` method takes one parameter:
 
@@ -50,6 +47,19 @@ To stop observing changes, invoke the `disconnect` method.
 MyAxeObserver.disconnect()
 ```
 
+### Interacting with the axe-core API
+
+The instance of axe-core used by agnostic-axe is exported by this module. Import it to interact with the [axe-core API](https://github.com/dequelabs/axe-core/blob/develop/doc/API.md).
+
+```js
+import('https://unpkg.com/agnostic-axe@3').then(
+  ({ axeCoreInstance AxeObserver, logViolations }) => {
+    axeCoreInstance.registerPlugin(myPlugin)
+    // ...
+  }
+)
+```
+
 ## Comparison with react-axe
 
 Unlike framework specific implementations of [axe-core](https://github.com/dequelabs/axe-core), such as [react-axe](https://github.com/dequelabs/react-axe), agnostic axe uses a [MutationObserver](https://developer.mozilla.org/en-US/docs/Web/API/MutationObserver) to listen for changes directly in the DOM. This has two advantages:

src/AxeObserver.mjs

@@ -1,26 +1,27 @@
 import axeCore from 'axe-core'
 import AuditQueue from './AuditQueue.mjs'
 
+// Apply default axeCore config
+axeCore.configure({
+  reporter: 'v2',
+  checks: [
+    {
+      id: 'color-contrast',
+      options: {
+        // Prevent axe from automatically scrolling
+        noScroll: true
+      }
+    }
+  ]
+})
+
+export const axeCore
+
 // The AxeObserver class takes a violationsCallback, which is invoked with an
 // array of observed violations.
 export default class AxeObserver {
   constructor(
-    violationsCallback,
-    {
-      axeCoreConfiguration = {
-        reporter: 'v2',
-        checks: [
-          {
-            id: 'color-contrast',
-            options: {
-              // Prevent axe from automatically scrolling
-              noScroll: true
-            }
-          }
-        ]
-      },
-      axeCoreInstanceCallback
-    } = {}
+    violationsCallback
   ) {
     if (typeof violationsCallback !== 'function') {
       throw new Error(
@@ -43,14 +44,6 @@ export default class AxeObserver {
 
     // AuditQueue sequentially runs audits when the browser is idle.
     this._auditQueue = new AuditQueue()
-
-    // Allow for registering plugins etc
-    if (typeof axeCoreInstanceCallback === 'function') {
-      axeCoreInstanceCallback(axeCore)
-    }
-
-    // Configure axe
-    axeCore.configure(axeCoreConfiguration)
   }
   observe(targetNode) {
     if (!targetNode) {

src/index.mjs

@@ -1,5 +1,8 @@
-import _AxeObserver from './AxeObserver.mjs'
+import _AxeObserver, {
+  axeCoreInstance as _axeCoreInstance
+} from './AxeObserver.mjs'
 import _logViolations from './logViolations.mjs'
 
 export const AxeObserver = _AxeObserver
+export const axeCoreInstance = _axeCoreInstance
 export const logViolations = _logViolations

src/logViolations.mjs

@@ -1,4 +1,4 @@
-import axeCore from 'axe-core'
+import { axeCoreInstance } from './AxeObserver'
 
 const boldCourier = 'font-weight:bold;font-family:Courier;'
 const critical = 'color:red;font-weight:bold;'
@@ -64,7 +64,9 @@ function logHtml(node) {
 }
 
 function logFailureMessage(node, key) {
-  var message = axeCore._audit.data.failureSummaries[key].failureMessage(
+  var message = axeCoreInstance._audit.data.failureSummaries[
+    key
+  ].failureMessage(
     node[key].map(function(check) {
       return check.message || ''
     })