{"id":557,"date":"2014-07-09T11:56:06","date_gmt":"2014-07-09T11:56:06","guid":{"rendered":"http:\/\/www.siriinnovations.com\/blog\/?p=557"},"modified":"2019-04-10T15:03:08","modified_gmt":"2019-04-10T09:33:08","slug":"decoupling-custom-jquery-events","status":"publish","type":"post","link":"https:\/\/siriinnovations.com\/blog\/decoupling-custom-jquery-events\/","title":{"rendered":"Decoupling with custom jQuery events"},"content":{"rendered":"

Introduction:<\/strong><\/p>\n

Decoupling is when we remove these unnecessary relationships, allowing units of code to function independently. Applications should be able to function independently or with other apps in a container (think widgets).<\/p>\n

While the concept of\u00a0custom events in jQuery<\/a>\u00a0may not be a new one, I tend to only see them used amongst plugins, mainly to keep their events namespaced for fear of collusion with other events.<\/p>\n

The truth is they can be leveraged in everyday and jQuery code to help make life a little easier.<\/p>\n

The problem<\/strong><\/p>\n

It\u2019s not uncommon to see a single event handler finding itself responsible for many things:<\/p>\n

\n
$('.add-items').on('click', function(event) {\r\n$('.loading-message').show();\r\n$.ajax({\r\n\/\/ etc\r\n});\r\n$('.something-else').addClass('foo')\r\nevent.preventDefault();\r\n});<\/pre>\n<\/div>\n
Having an event handler responsible for a lot of different tasks will typically result in large, incoherent event callbacks. These can often get worse when other developers have to add in additional functionality later.<\/p>\n
Decoupling all the things<\/strong><\/p>\n
One route I like to take is to separate the logic relating to the DOM event.This means just handling anything related to the event (preventDefault\u00a0or stopPropagation\u00a0calls, for example) and then firing a custom event and allowing another part of the application handle the \u2018business\u2019 side of things:<\/p>\n
\n
var doc = $(document);\r\n$('.add-items').on('click', function(event) {\r\ndoc.trigger('addItem', [$(this)]);\r\nevent.preventDefault();\r\n});<\/pre>\n<\/div>\n
The first thing to note is that I\u2019m grabbing a reference to the document wrapped as a jQuery object:<\/p>\n
\n
var doc = $(document);<\/pre>\n<\/div>\n
By triggering the events on this global object, it can become a sort of mediator between other parts of code.<\/p>\n
Storing a reference to it outside of the event handler callback also means that it won\u2019t be created each time the button is clicked. This is a good practice to get in the habit of.<\/p>\n
Then all that is required is to trigger an event of our choice and pass any useful data along with it.<\/p>\n
\n
doc.trigger('addItem', [$(this)]);<\/pre>\n<\/div>\n
An object or array can be passed along with the event.\u00a0In this case i am passing along a jQuery object that refers to the clicked button.<\/p>\n
Responding to the event<\/strong><\/p>\n
Listening for the\u00a0addItem\u00a0event is as simple as creating an event listener on the\u00a0documentobject:<\/p>\n
\n
$(document).on('addItem', function(event, btnElement) {\r\n$('.something-else').addClass('foo')\r\n});\r\n$(document).on('addItem', function(event, btnElement) {\r\n$.ajax({\r\n\/\/ etc\r\n});\r\n});<\/pre>\n<\/div>\n
The event object in the above callback handlers are related to the\u00a0add Itemcustom event and have nothing to do with the earlier click event.<\/p>\n
Now the logic is nicely separated, and additional chunks of functionality can be added or removed without any need to worry about the other parts of the application.<\/p>\n
And seeing as the global\u00a0document\u00a0object was chosen to be the mediator, these events can be attached in other places (perhaps a different file completely) without any extra effort.<\/p>\n
It seems like a bit more work initially, but as the code expands, this way of decoupling events will start to pay back in droves.<\/p>\n","protected":false},"excerpt":{"rendered":"
Introduction: Decoupling is when we remove these unnecessary relationships, allowing units of code to function independently. Applications should be able to function independently or with other apps in a container (think widgets). While the concept of\u00a0custom events in jQuery\u00a0may not be a new one, I tend to only see them used amongst plugins, mainly to […]<\/p>\n","protected":false},"author":13,"featured_media":719,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,3,6],"tags":[115,60],"class_list":["post-557","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-jquery","category-technical","category-tutorials","tag-decoupling","tag-jquery-2"],"yoast_head":"\nDecoupling with custom jQuery events - Siri Innovations<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/siriinnovations.com\/blog\/decoupling-custom-jquery-events\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Decoupling with custom jQuery events - Siri Innovations\" \/>\n<meta property=\"og:description\" content=\"Introduction: Decoupling is when we remove these unnecessary relationships, allowing units of code to function independently. 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