WordCamp Ann Arbor 2017 JavaScript Workshop

JavaScript for WordPress Zac Gordon @zgordon https://javascriptforwp.com

Go Here to Get Setup javascriptforwp.com/wca2

Are We Ready?! 1. Slides and Example Files 2. Code
Editor (I’m using Atom) 3. Local WordPress Install (I’m Using Local)

Workshop Overview 1. JavaScript [ JS 101, DOM, Events ]
2. The WordPress REST API [ Accessing, Arguments ] 3. JavaScript & WP API in Themes [ Enqueuing, jQuery, API ] 4. Homework!

JS 101 Pop Quiz!

JS 101 Pop Quiz!!! 1. What is a variable? 2.
What is an array? 3. What is a function? 4. What is an Object? 5. What is a Loop? 6. What is a Conditional 7. How do you include JavaScript in HTML? 8. How do you include JavaScript in a WordPress Theme?

JS 101

Variable A container for storing values (in memory) var username
= 'zgordon'; let username = 'zgordon'; const siteURL = 'https://site.com';

keyword var let const global scope YES NO NO function
scope YES YES YES block scope NO YES YES can be reassigned YES YES NO

Variable A container for storing values (in memory) var username
= 'zgordon', twitter = '@zgordon', website = 'zacgordon.com';

Array A collection of values var postIds = [ 1,
2, 3, 5 ]; var usernames = [ 'zgordon', 'admin' ];

Array A collection of values (zero indexed) var postIds =
[ 1, 2, 3, 5 ]; postIds[ 0 ] // Equals 1 postIds[ postIds.length - 1 ] // Last item

Functions Let us write, call and reuse blocks of code
function getPosts() { // Function Declaration var posts = apiMagic(); // Will learn.. return posts; } getPosts(); // Function Call getPosts // Function Reference

Function Parameters Can pass data into functions function getUser( id
= 0 ) { var user = apiMagic( id ); return user; } getUser( 1 );

Objects Container with properties (values) and methods (functions). var post
= { title: 'Hello World!', render: function() { console.log( this.title ); } } post.title; post.render();

Loops Let us perform an action on a collection of
items. var postIds = [ 1, 7, 14, 34, 88, 117 ]; for ( let i = 0, max = postIds.length; i < max; i++ ) { console.log( 'Post #' + postIds[ i ] ); }

For Of Loop Lets us loop through an array var
postIds = [ 1, 7, 14 ]; for( let id of postIds ) { console.log( id ); }

For Each Method Lets us loop through an array var
postIds = [ 1, 7, 14 ]; postIds.forEach( id => { console.log( id ) } );

Mapping Mapping is a functional alternative to looping var postIds
= [ 1, 7, 14 ]; postIds.map( id => { console.log( id ); });

Conditional Statements Tests to determine what code to run var
loggedIn = true; if ( true === loggedIn ) { console.log( 'Show dashboard' ); } else { console.log( 'Please login' ); }

Include JS in HTML <html> <head> </head> <body> <script> console.log(
'JS Running!' ); </script> </body> </html>

Include JS in HTML <html> <head> </head> <body> <script src="index.js"></script>
</body> </html>

Include JS in WP Theme function my_theme_scripts() { wp_enqueue_script( 'main-js',
get_template_directory_uri() . '/js/main.js', [ 'jquery', 'wp-api' ], time(), true ); } add_action( 'wp_enqueue_scripts', ‘my_theme_scripts' );

The DOM & Nodes

The DOM is an API For HTML (XML & SVG)

BROWSER DOM HTML JavaScript

Build documents, navigate their structure, and add, modify, or delete
elements and content.

Everything in the DOM Is a Node

Common Node Types • Document [9] • DocumentType [10] •
Element [1] • Text [3] • Comments [8] • DocumentFragments [11]

10 Doctype Root / HTML 1 Body 1 Head 1
1 Title 3 Title Text 1 Header 1 Paragraph 3 Header Text 3 Text 1 Link 3 3 Link Text 9 Document Window

WordCamp Miami 2017 Getting DOM Nodes w JS document.getElementById( 'main'
) document.getElementsByTagName( 'a' ) document.getElementsByClassName( 'post' ) document.querySelector( '.entry-title a' ) document.querySelectorAll( '.entry-title a' ) el.querySelector( 'a' )

WordCamp Miami 2017 Getting Node Values el.innerText el.innerHTML el.id el.href
el.dataset.custom input.value var el = document.getElementById( 'main' );

WordCamp Miami 2017 Setting Node Values el.innerText = 'New'; el.innerHTML
= '<p>New</p>'; input.value = 'zgordon'; @zgordon var el = document.getElementById( 'main' ); WordCamp DC 2017

PRACTICE 1.1 Getting & Setting Nodes w JS

WordCamp Miami 2017 Creating & Appending   Nodes

WordCamp Miami 2017 Creating Nodes document.createElement( 'p' ) document.createTextNode( 'Text'
)

WordCamp Miami 2017 Appending Nodes parent.appendChild( newEl ); parent.insertBefore( newEl,
el );

WordCamp Miami 2017 Appending Nodes Example var pEl = document.querySelector(
'p' ), aEl = document.createElement( 'a' ), aText = document.createTextNode( 'Link' ); aEl.appendChild( aText ); aEl.href = 'https://javascriptforwp.com'; pEl.appendChild( aEl );

WordCamp Miami 2017 “Hacker Style” Appending Nodes var pEl =
document.querySelector( 'p' ), markup = ''; markup += '<a href="https://site.com">'; markup += 'Link Text'; markup += '</a>'; pEl.innerHTML = markup;

Practice 1.2 + 1.3  Creating & Appending Nodes

Events w JavaScript

WordCamp Miami 2017 Types of Events • Mouse events •
Keyboard events • Form events • Media events • Drag and Drop events • Window events • Many more….

WordCamp Miami 2017 Hooking into Events w JavaScript 1. Inline
in HTML 2. Global 1 Off 3. Listeners Best <a onclick="alert('hi')">Alert</a> a.onclick = sayHi a.addEventListener( 'click’, sayHi, false )

WordCamp Miami 2017 Event Listeners var linkEl = document.querySelector( 'a'
); function displayLinkInfo( event ) { event.preventDefault(); console.log( event ); } linkEl.addEventListener( 'click', displayLinkInfo, false );

WordCamp Miami 2017 The Event Object link.addEventListener( 'click', sayHi );
function sayHi( event ) { console.log( event ); console.log( event.type ); console.log( event.target ); }

WordCamp Miami 2017 Removing Event Listeners var el = document.querySelector(
'a' ); el.addEventListener( 'click', sayHi, false ); el.removeEventListener( 'click', sayHi, false );

WordCamp Miami 2017 Removing Event Listeners var el = document.querySelector(
'a' ); el.addEventListener( 'click', sayHi, false ); el.remove(); // Listener still exists el = null; // Listener does NOT exist

Practice 1.4 Event Listeners Practice

The WordPress   REST API

The WP REST API Allows us to get, save, edit,
and remove content from WordPress using JavaScript.

The WordPress REST API /wp-json/wp/v2/posts /wp-json/wp/v2/revisions /wp-json/wp/v2/categories /wp-json/wp/v2/tags /wp-json/wp/v2/pages /wp-json/wp/v2/comments
/wp-json/wp/v2/taxonomies /wp-json/wp/v2/media /wp-json/wp/v2/users /wp-json/wp/v2/types /wp-json/wp/v2/statuses /wp-json/wp/v2/settings /wp-json/custom/v1/something /wp-json/another/v3/else

The WordPress REST API To access all of the posts
for your site: https://yoursite.com/wp-json/wp/v2/posts To access a post with an ID of “1” for your site: https://yoursite.com/wp-json/wp/v2/posts/1

The WordPress REST API To access all of the pages
for your site: https://yoursite.com/wp-json/wp/v2/pages To access a page with an ID of “5” for your site: https://yoursite.com/wp-json/wp/v2/pages/5

You can pass arguments to API URLs to customize what
you get back.

The WordPress REST API https://yoursite.com/wp-json/wp/v2/posts ? per_page=10  &_embed  &search=hello%20world  &orderby=title 
&order=asc https://developer.wordpress.org/rest-api/reference/posts/#arguments

Practice 2.1  WP API in the Browser

WordPress API w AJAX + JS

AJAX Allows for us to make calls to the WP
REST API and get back content in a format JavaScript can understand. (Can also save, edit and delete)

Ways to Make JS AJAX Calls • XMLHttpRequests() • fetch()
• jQuery • Axios • API Clients (Backbone, Node)

AJAX Behind the Scenes 1. Request a URL 2. Get
JSON in return 3. Parse JSON into Native JavaScript 4. Use Native JavaScript

Pseudo AJAX var postsJSON = fetch('https://wp.dev/wp-json/wp/v2/posts'), posts = JSON.parse( postsJSON
); for( let post of posts ) { renderPost( post ); }

AJAX with Axios axios({ method: 'get', url: 'https://example.dev/wp-json/wp/v2/posts', params: {
per_page: 3 } }) .then( function( response ) { for( let post of response.data ) { renderPost( post ); } });

Practice 2.2 + 2.3  WP API with Axios Ajax

JS + API Inside of WP

Enqueuing JavaScript The process of loading JavaScript into a theme
or the admin area via PHP functions. wp_enqueue_script() wp_localize_script()

function my_theme_scripts() { wp_enqueue_script( 'main-js', // Unique name get_template_directory_uri() .
'/js/main.js', // Path [ 'jquery', 'wp-api' ], // Dependencies time(), // Version true ); // Include in footer (v header) } add_action('wp_enqueue_scripts', 'my_theme_scripts', 999); wp_enqueue_script()

function my_theme_scripts() { wp_enqueue_script( 'main-js', ... ); wp_localize_script( 'main-js', 'myGlobalVars',
[ 'siteUrl' => esc_url( home_url() ), 'siteName'=> get_bloginfo( 'name' ) ] ); } add_action('wp_enqueue_scripts', 'my_theme_scripts', 999); wp_localize_script()

functions.php function my_theme_scripts() { wp_enqueue_script( 'main-js', ... ); wp_localize_script( 'main-js',
'myGlobalVars', ... ); } add_action('wp_enqueue_scripts', 'my_theme_scripts', 999); main.js console.log( myGlobalVars.siteUrl ); wp_localize_script()

function my_theme_scripts() { wp_enqueue_script( 'main-js', ... ); wp_localize_script( 'main-js', 'myGlobalVars',
... ); } add_action( 'wp_enqueue_scripts', 'my_theme_scripts', 999); add_action( 'admin_enqueue_scripts', 'my_theme_scripts', 999 ); Enqueuing JS in Admin Area

function my_admin_scripts( $hook ) { global $main_menu_url; if( $hook !=
'toplevel_page_' . $main_menu_url ) return; wp_enqueue_script( 'my-admin-js', plugins_url( '/assets/js/ admin.js', __FILE__ ), [ 'wp-api' ], time(), true ); } add_action( 'admin_enqueue_scripts', 'my_admin_scripts', 999); Enqueuing JS in Admin Area

Practice 3.1  Enqueuing JavaScript in a Theme

jQuery + WordPress

WordPress comes with Several JS Libraries Available to Us

'/js/main.js', // Path [ 'jquery' ], // Dependencies time(), // Version true ); // Include in footer (v header) } add_action('wp_enqueue_scripts', 'my_theme_scripts', 999); jQuery Dependency

The $ in jQuery is NOT available by default

jQuery( ‘.this-works' ).show();

(function( $ ) { $('.this-works').show(); })( jQuery ); Immediately Evoked
Function Expression (IEFE)

Practice 3.2  Using jQuery for AJAX

The Backbone WP API Client

Backbone API Client Allows us to easily use the WP
REST API in a theme or plugin without writing AJAX or authentication. No knowledge of Backbone necessary*

'/js/main.js', // Path [ ‘wp-api’ ], // Dependencies time(), // Version true ); // Include in footer (v header) } add_action('wp_enqueue_scripts', 'my_theme_scripts', 999); Backbone API Client Dependency

var posts = new wp.api.collections.Posts(); posts.fetch({ data: { per_page: 3
} }) .done( () => { posts.each( post => renderPost( post.attributes ); ); Backbone Client - Get Posts

var post = new wp.api.models.Post( { id } ); post.fetch()
.done( () => renderPost( post.attributes ) ); Backbone Client - Get Post By ID

Practice 3.3  Using the Backbone API Client

WordCamp Miami 2017 javascriptforwp.com/wca2 Learn JavaScript Deeply with Zac Gordon
@zgordon Thanks!

WordCamp Ann Arbor 2017 JavaScript Workshop

WordCamp Ann Arbor 2017 JavaScript Workshop

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