Visualforce Developer Guide

Introducing Visualforce
Tools for Visualforce Development
Getting a Quick Start with Visualforce
Customizing the Appearance and Output of Visualforce Pages
Standard Controllers
Standard List Controllers
Custom Controllers and Controller Extensions
Advanced Examples
Override Buttons, Links, and Tabs with Visualforce
Using Static Resources
Creating and Using Custom Components
Dynamic Visualforce Bindings
Dynamic Visualforce Components
Integrate Email with Visualforce
Visualforce Charting
Creating Maps with Visualforce
Render Flows with Visualforce
Templating with Visualforce
Developing Salesforce Apps with Visualforce
Adding Visualforce to a Salesforce AppExchange App
Using JavaScript in Visualforce Pages
Communicating Across the DOM with Lightning Message Service
Visualforce Best Practices
Standard Visualforce Component Reference
Appendices
Global Variables, Functions, and Expression Operators
Global Variables
$Action
$Api
$Asset
$Cache.Org
$Cache.Session
$Component
$ComponentLabel
$CurrentPage
$FieldSet
$Label
$Label.Site
$MessageChannel
$Network
$ObjectType
$Organization
$Page
$Permission
$Profile
$Resource
$SControl
$Setup
$Site
$System.OriginDateTime
$User
$User.UITheme and and $User.UIThemeDisplayed
$UserRole
Functions
Expression Operators
Security Tips for Apex and Visualforce Development
Apex Classes Used in Visualforce Controllers
Execution Governors and Limits
PDF

Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

$Resource

A global merge field type to use when referencing an existing static resource by name in a Visualforce page. You can also use resource merge fields in URLFOR functions to reference a particular file in a static resource archive.

Usage

Use {!$Resource} to reference an existing static resource. The format is {!$Resource.nameOfResource}, such as {!$Resource.TestImage}.

Examples

The Visualforce component below references an image file that was uploaded as a static resource and given the name TestImage: 
1<apex:image url="{!$Resource.TestImage}" width="50" height="50"/>
To reference a file in an archive (such as a .zip or .jar file), use the URLFOR function. Specify the static resource name that you provided when you uploaded the archive with the first parameter, and the path to the desired file within the archive with the second. For example:
1<apex:image url="{!URLFOR($Resource.TestZip,
2                  'images/Bluehills.jpg')}" width="50" height="50"/>

You can also use dynamic references to reference static resources. For example, {!$Resource[appLogo]}, assuming there is an appLogo property or getAppLogo() method in your page’s controller.