<img width="256" height="256" src="https://rawgit.com/virtyaluk/mutation-watcher/master/media/mutation-watcher.png" alt="mutation-watcher">
<br>
<br>
MutationWatcher is a JavaScript library that comes to help make DOM mutation observing fast and easy.
MutationWatcher uses
MutationObserver API (in new browsers) or old-fashioned (deprecated) way with
Mutation events (in browsers that doesn't support newest API) as a way to react to changes in DOM. Actually it works in all browsers that support any of this APIs.
Install
bower:
```
$ bower install mutation-watcher
```
npm
```
$ npm install mutation-watcher
```
Usage
```js
// Querying the target element
var target = document.querySelector('#signin-button');
// Options
var options = { attributes:
'pressed', 'focused', 'active' };
// Creating the watcher instance
var watcher = new MutationWatcher(function(mutationData) { console.log(mutationData); });
// Finally starting the watcher
watcher.watch(target, options);
// Disconnecting from it
watcher.disconnect();
```
API
The
MutationWatcher library exports a single object - class called
MutationWatcher
. The class allows to create a new instance of DOM mutation watcher.
Constructor
MutationWatcher()
Constructor for instantiating new DOM mutation watchers.
```js
MutationWatcher(
function callback,
bool customEvents
);
```
Parameters
callback
. Optional. Defaults to null
. The function which will be called per each DOM mutation. The watcher will call this function with two arguments. The first is a MutationData object. The second is the current instance of a MutationWatcher
.
customEvents
. Optional. Defaults to false
if callback
provided and true
if callback
is null
. If set to true
then custom events will be triggered on specified target.
Note
If the class instance created without any argument, then
customEvents
will be set to
true
by default.
If no
callback
provided or it's
null
then all
MutationData objects will be added to the queue and available to return using takeRecords method.
Instance methods
- void watch( Object target, Object options );
watch() #####
Registers the MutationWatcher
instance to receive notifications of DOM mutations on the specified node.
```js
void watch(
Object target,
Object options
);
```
Parameters
target
. Optional. Defaults to window.document
. The Node or a string representing the CSS selector for target node on which to observe DOM mutations.
options
. Optional. Defaults to all
. An options object specifies which DOM mutations should be reported.
Note
If no target
provided then the window.document
will be used.
If options
object not provided then default options will be used.
disconnect()
Stops the MutationWatcher
instance from receiving notifications of DOM mutations. Until the watch() method is used again, watcher's callback will not be invoked.
```js
void disconnect();
```
takeRecords()
Empties the MutationWatcher
instance's record queue and returns what was in there.
```js
Array takeRecords();
```
Return value
Returns an Array of MutationData objects.
MutationWatcher Options
MutationWatcher
options is an object which can specify the following properties:
attributes
- Set to true
if mutations to target's attributes are to be observed.
elements
- Set to true
if additions and removals of the target node's child elements (including text nodes) are to be observed.
characterData
- Set to true
if mutations to target's data are to be observed.
subtree
- Set to true
if mutations to not just target, but also target's descendants are to be observed.
attributeOldValue
- Set to true
if attributes is set to true
and target's attribute value before the mutation needs to be recorded.
characterDataOldValue
- Set to true
if characterData is set to true
and target's data before the mutation needs to be recorded.
matchAttributes
- Set to an array of attribute local names (without namespace) if not all attribute mutations need to be observed.
matchElements
- Set to an array of CSS selectors or html elements if not all element mutations need to be observed.
matchCharacterDataElements
- Set to an array of CSS selectors or html elements if not all characterData mutations need to be observed.
all
- Shorthand. Set to true if attributes
, elements
and characterData
need to be observed.
Default options
Options can be passed to watch() method as a plain string with single option or as an object with a combination of options.
```js
// Single option can be passed as a string
var singleOption = 'attributes'; // or 'elements', 'characterData', 'all'
watcher1.watch(callback, singleOption);
// To combine options use object notation
var optionsObj = {
elements: true,
subtree: true,
// Filter elements
matchElements: ['img.photo', 'div.wall-post', actualNodeElement]
};
watcher2.watch(callback, optionsObj);
// or
optionsObj = {
elements: ['img.photo', 'div.wall-post', actualNodeElement],
subtree: true
};
watcher3.watch(callback, optionsObj);
```
If watch() called without the options or it's null
then default options will be used. The default options object looks following:
```js
var watcher = new MutationWatcher(callback);
watcher.watch(target, null);
console.log(watcher.config);
/ prints out
{
attributes: true,
elements: true,
characterData: true,
attributeOldValue: true
characterDataOldValue: true,
subtree: false
}
/
```
MutationData
MutationData
is the object that will be passed to the observer's callback
. It has the following properties:
Property | Type | Description
--- | --- | ---
type | String | Returns attributes
if the mutation was an attribute mutation, characterData
if it was a mutation to a CharacterData node, and elements
if it was a mutation to the tree of nodes.
target | Node | Returns the node the mutation affected, depending on the type. For attributes, it is the element whose attribute changed. For characterData, it is the CharacterData node. For elements, it is the node whose children changed.
addedNodes |
NodeList | Return the nodes added. Will be a
null
if no nodes were added.
removedNodes |
NodeList | Return the nodes removed. Will be a
null
if no nodes were removed.
previousSibling |
Node | Return the previous sibling of the added or removed nodes, or
null
.
nextSibling |
Node | Return the next sibling of the added or removed nodes, or
null
.
attributeName | String | Returns the local name of the changed attribute, or
null
.
attributeNamespace | String | Returns the namespace of the changed attribute, or
null
.
oldValue | String | The return value depends on the type. For attributes, it is the value of the changed attribute before the change. For characterData, it is the data of the changed node before the change. For elements, it is
null
.
newValue | String | The return value dependents on the type. For attributes, it is the value of the changed attribute after the change. For characterData, it is the data of the changed node after the change. For elements, it is
null
.
Custom Events
It's possible to subscribe to custom mutation events instead of using
callback
passed to the constructor.
Default event names can be changed using the static object called
customEventsNames
on
MutationWatcher class.
To enable custom events on a specific target, it needs to set
customEvents
property to
true
and invoke
watch() method with or without any arguments.
```js
var watcher = new MutationWatcher(null, true);
watcher.watch(myButton);
// Subscribing for attribute change
myButton.addEventListener(MutationWatcher.customEventsNames.attributes, function(event) {
// Mutation data available in `details` property
var mutationData = event.details;
}, false);
```
Supported browsers:
Running tests
Install dependencies:
```shell
$ npm install
```
Run them:
```shell
$ grunt test
```
Changelog
1.0.2 - September 7, 2015
- Moved from jshint to eslint
Author
Bohdan Shtepan
http://modern-dev.com
Please feel free to reach out to me if you have any questions or suggestions.
License
MIT