Drupal behaviors

drupal behaviors drupal 7 example
drupal behaviors on page load
drupal 8 jquery once example
drupal 8 pass variable to javascript
drupal jquery
drupal 8 inline javascript
drupal add js
drupal libraries
  • What are Drupal behaviors at all?
  • What type of service layer it offers to module developers?
  • What type of relation it maps to jQuery.ready?

Long version: Drupal.behaviors is not simply a replacement for jQuery.ready since the latter only runs once (when DOM is ready for manipulation): behaviors can be fired multiple times during page execution and can be run whenever new DOM elements are inserted into the document.

Also, modules could override or extend an existing behavior (e.g. if one module has a behavior of adding a bounce effect on all links, a second module could replace the behavior by a different bounce effect).

Short version: it's more modular, though the documentation could be improved.


Also, starting in Drupal 7, settings defined using drupal_add_js (PHP) or in Drupal.settings.modulename (Javascript) are directly passed as second parameter (the first one being the context) to the behavior.

For example:

Drupal.behaviors.changeLinks = function(context, settings){
    if (!settings) settings = Drupal.settings.changeLinks;
    $("a", context).hover(function() {
        $(this).css('color', settings.color);
    });
};

And if one of your script (or another) creates new nodes, it could still have the behaviors applied to the new nodes without having to know what other modules are iinstalled:

var newNodes = $('<a href="#">Hello</a> <a href="#">World</a>').appendTo('#someDiv');

Drupal.attachBehaviors(newNodes);

JavaScript API overview, attachBehaviors() function, which in turn cycles through the Drupal.behaviors object calling every one of its properties, these all being functions  Post A Job. Get Free Quotes. Hire Proven Drupal Developers. Anytime, Anywhere!


Drupal Behaviors, Below is an example of a Drupal Javascript Behavior. (function ($) { 'use strict'; Drupal.behaviors.awesome = { attach: function(context, settings) { $('main',  Drupal.behaviors can also override or even extend an existing behavior. So for instance, if a module behavior adds a bounce effect on all links, another module could replace that behavior with a different bounce effect.


Along with answers mentioned above on of the key things is you can pass data from php to javascript which is as follows

Passing values from PHP to Javascript with "Drupal.settings"

You can easily make variables from PHP available to Javascript on the front end with Drupal.settings using drupal_add_js() function

<?php
  drupal_add_js(array('myModule' => array('key' => 'value')), 'setting');
?>

or

<?php
$element['#attached']['js'][] = array(
  'type' => 'setting',
  'data' => array('myModule' => array('key' => 'value')),
);
?>

This will be available in Javascript as:

  if (Drupal.settings.myModule.key === 'value') {
    alert('Got it!');
  }

Better understanding of Drupal behaviors, In short, the advantage of Behaviors over document.ready() is that they are automatically re-applied to any content loaded through AJAX. Drupal behaviors ( Drupal.behaviors) namespace : A Drupal behavior has to have a unique namespace. attach : Contains the actual function that should be executed. context : The context variable is the part of the page for which this applies. settings : The settings variable is used to pass


Looking for a similar answer and arrived here, still without clues. Finally found a little more explanation (and examples) from an article here: https://benmarshall.me/drupal-behaviors/

I am not the original author, so I can only quote some texts:

What are Drupal Behaviors?

In short, Drupal.behaviors is a more modular and better way to implement jQuery.ready. Unlike jQuery.ready which only runs once when the DOM is ready for manipulation, Drupal.behaviors can be ran multiple times during page execution. Even better, they can be ran whenever new DOM elements are inserted into the document (i.e. AJAX driven content).

Drupal.behaviors can also override or even extend an existing behavior. So for instance, if a module behavior adds a bounce effect on all links, another module could replace that behavior with a different bounce effect.

Another added bonus of Drupal.behaviors (starting in Drupal 7), is the ability to use the drupal_add_js (PHP) or Drupal.settings.modulename (JS) and pass settings as a second parameter (the first being the context) to the behavior.

What are Drupal Behaviors?, Drupal has a 'behaviors' system to provide a modular and better way for attaching JavaScript functionality to place elements on a page. Drupal  Drupal Behaviors allows you to override or extend the existing behavior. Find out how this Drupal core functionality helps. Drupal is a versatile content management system that interlocks both the database and the server, which offers a revolutionary programming edge where there are options to insert the behavior to override JavaScript for an appealing interface.


Drupal has a ‘behaviors’ system to provide a modular and better way for attaching JavaScript functionality to place elements on a page. Drupal Behaviors allows you to override or extend the existing behavior. These Drupal behaviors are event triggered programs that get attached to the page elements to be changed. While behaviours can be attached to specific contents, multiple behaviours are also attached and can be ablazed multiple times for a quick remake.

JavaScript by attaching logic to Drupal.behaviors. Here is an example taken from that page:

Drupal.behaviors.exampleModule = {
  attach: function (context, settings) {
    $('.example', context).click(function () {
      $(this).next('ul').toggle('show');
    });
  }
}

;

Drupal behaviors: A quick how to | Amazee Labs, Drupal.behaviors.infiniteScrollAddClass = { attach: function (context, settings) { $('​.view-display-id-page .views-row').addClass  The behaviors will be executed on every request including AJAX requests, so let's do the equivalent of the code above but this time using this method: Drupal.behaviors.infiniteScrollAddClass = { attach: function (context, settings) { $('.view-display-id-page .views-row').addClass('fancy-pants'); } };


Drupal Behaviors: A Quick Introduction & How-to, Ever hear of Drupal Behaviors? Well if not and your coding JS in Drupal you're probably doing it wrong… or at least not the 'Drupal way'. Drupal behaviors that take the context variable into account when selecting portions of the DOM such as $ ('#some-id', context) will be quickly skipped since they won’t find what they are looking for. Unfortunately, it is a common mistake to overlook this and not use the context variable in jQuery selectors.


Drupal.behaviors and Drupal-Specific Javascript, Topics include using Drupal.behaviors and variable settings. There where a couple of changes to the Drupal.behaviors system for D7. You can find out more​  What are Drupal Behaviors? In short, Drupal.behaviors is a more modular and better way to implement jQuery.ready. Unlike jQuery.ready which only runs once when the DOM is ready for manipulation, Drupal.behaviors can be ran multiple times during page execution.


Drupal 8, behaviors, and jQuery Once, Drupal 8, behaviors, and jQuery Once. When porting some front-end code from Drupal 7 to Drupal 8, I ran into an unexpected change in the use of jQuery.once()​  Drupal provides a central object called Drupal.behaviors with which JavaScript functions may register to ensure that rebinding of behaviors takes place when necessary. The following version of plusone.js allows voting via AJAX just like the previous version but safeguards our bindings by registering with Drupal.behaviors: