arrive.js

arrive.js provides events to watch for DOM elements creation and removal. It makes use of Mutation Observers internally.

Download arrive.min.js (latest)

or use Bower to install:

# install arrive.js and add it to bower.json dependencies
$ bower install arrive --save

Node.js / NPM

Node.js users can install using npm:

$ npm install arrive --save

Usage

The library does not depend on jQuery, you can replace jQuery elements in the examples below with pure javascript elements and it would work fine.

Watch for elements creation

Use arrive event to watch for elements creation:

// watch for creation of an element which satisfies the selector ".test-elem"
$(document).arrive(".test-elem", function() {
    // 'this' refers to the newly created element
    var $newElem = $(this);
});

// the above event would watch for creation of element in whole document
// it's better to be more specific whenever possible, for example
$(".container-1").arrive(".test-elem", function() {
    var $newElem = $(this);
});

// as of v2.3.2, new element is also passed as argument to the callback function.
// This is to support arrow functions as 'this' is not bindable in arrow functions.
$(document).arrive(".test-elem", function(newElem) {
    var $newElem = $(newElem);
});

In pure javascript you can call the function on document, window, any HTMLElement or NodeList, like this:

// watch for element creation in the whole HTML document
document.arrive(".test-elem", function() {
    // 'this' refers to the newly created element
});

// this will attach arrive event to all elements in the NodeList
document.getElementsByClass(".container-1").arrive(".test-elem", function() {
    // 'this' refers to the newly created element
});

Make sure to remove listeners when they are no longer needed, it's better for performance:

// unbind all arrive events on document element
$(document).unbindArrive();

// unbind all arrive events on document element which are watching for ".test-elem" selector
$(document).unbindArrive(".test-elem");

// unbind only a specific callback
$(document).unbindArrive(callbackFunc);

// unbind only a specific callback on ".test-elem" selector
$(document).unbindArrive(".test-elem", callbackFunc);

// unbind all arrive events
Arrive.unbindAllArrive();

Options

As of v2.0 arrive event accepts an optional options object as 2nd argument. Options object consists of following:

var options = {
    fireOnAttributesModification: boolean, // Defaults to false. Setting it to true would make arrive event fire on existing elements which start to satisfy selector after some modification in DOM attributes (an arrive event won't fire twice for a single element even if the option is true). If false, it'd only fire for newly created elements.
    onceOnly: boolean                      // Defaults to false. Setting it to true would ensure that registered callbacks fire only once. No need to unbind the event if the attribute is set to true, it'll automatically unbind after firing once.
    existing: boolean                      // Defaults to false. Setting it to true would ensure that the registered callback is fired for the elements that already exist in the DOM and match the selector. If options.onceOnly is set, the callback is only called once with the first element matching the selector.
};

Example:

$(document).arrive(".test-elem", {fireOnAttributesModification: true}, function() {
    // 'this' refers to the newly created element
    var $newElem = $(this);
});

Watch for elements removal

Use leave event to watch for elements removal. The first arugument to leave must not be a descendent or child selector i.e. you cannot pass .page .test-elem, instead, pass .test-elem. It's because of a limitation in MutationObserver's api.

// watch for removal of an element which satisfies the selector ".test-elem"
$(".container-1").leave(".test-elem", function() {
    var $removedElem = $(this);
});

You can unbind the leave event in the same way as arrive event, using unbindLeave function i.e:

// unbind all leave events on document element
$(document).unbindLeave();

// unbind all leave events
Arrive.unbindAllLeave();

Browser Support

arrive.js is built over Mutation Observers which is introduced in DOM4. It's supported in latest versions of all popular browsers.

Browser	Supported Versions
Google Chrome	27.0+
Firefox	14.0+
Safari	6.1+
Internet Explorer	11.0+
Opera	14.0+

Contributing

Report a bug / Request a feature

If you want to report a bug or request a feature, use the Issues section. Before creating a new issue, search the existing ones to make sure that you're not creating a duplicate. When reporting a bug, be sure to include OS/browser version and steps/code to reproduce the bug, a JSFiddle would be great.

Development

If you want to contribute to arrive, here is the workflow you should use:

1. Fork the repository.
2. Clone the forked repository locally.
3. From the dev branch, create and checkout a new feature branch to work upon. (If you want to work on some minor bug fix, you can skip this step and continue to work in dev branch)
4. Make your changes in that branch (the actual source file is /src/arrive.js).
5. If sensible, add some jasmine tests in /tests/spec/arriveSpec.js file.
6. Make sure there are no regressions by executing the unit tests by opening the file /tests/SpecRunner.html in a browser. There is a button 'Run tests without jQuery' at the top left of th page, click that button to make sure that the tests passes without jQuery. Run the test cases in all major browsers.
7. Push the changes to your github repository.
8. Submit a pull request from your repo back to the original repository.
9. Once it is accepted, remember to pull those changes back into your develop branch!

Keywords

javascript, js, jquery, node.js, watch, listen, creation, dynamically, removal, new, elements, DOM, dynamic, detect, insertions, event, bind, live, livequery