# Write a plugin
A plugin is simply a function that takes `hook` as an argument. The hook supports handling of asynchronous tasks.
## Full configuration
```js
window.$docsify = {
plugins: [
function(hook, vm) {
hook.init(function() {
// Called when the script starts running, only trigger once, no arguments,
});
hook.beforeEach(function(content) {
// Invoked each time before parsing the Markdown file.
// ...
return content;
});
hook.afterEach(function(html, next) {
// Invoked each time after the Markdown file is parsed.
// beforeEach and afterEach support asynchronous。
// ...
// call `next(html)` when task is done.
next(html);
});
hook.doneEach(function() {
// Invoked each time after the data is fully loaded, no arguments,
// ...
});
hook.mounted(function() {
// Called after initial completion. Only trigger once, no arguments.
});
hook.ready(function() {
// Called after initial completion, no arguments.
});
}
]
};
```
!> You can get internal methods through `window.Docsify`. Get the current instance through the second argument.
## Example
#### footer
Add footer component in each pages.
```js
window.$docsify = {
plugins: [
function(hook) {
var footer = [
'
',
''
].join('');
hook.afterEach(function(html) {
return html + footer;
});
}
]
};
```
### Edit Button
```js
window.$docsify = {
plugins: [
function(hook, vm) {
hook.beforeEach(function(html) {
var url =
'https://github.com/docsifyjs/docsify/blob/master/docs/' +
vm.route.file;
var editHtml = '[đź“ť EDIT DOCUMENT](' + url + ')\n';
return (
editHtml +
html +
'\n----\n' +
'Last modified {docsify-updated} ' +
editHtml
);
});
}
]
};
```
## Tips
### Get docsify version
```
console.log(window.Docsify.version)
```
Current version: loading