Principle 2: Operable Guidelines
WCAG Operable Success Criteria
User interface components and navigation must be operable. This means that users must be able to operate the interface. All web page elements must be operable by a keyboard, speech input, and other non-mouse devices. Some of the Java scripts may not be keyboard accessible, and preventing non-mouse users from performing some functions. Many people do not use the mouse and rely on the keyboard to interact with the web. This requires keyboard access to all functionality, including form controls, input, and other user interface components.
Guideline 2.1 Keyboard Accessible
The intent of this Success Criterion is to ensure that, wherever possible, content can be operated through a keyboard or keyboard interface (so an alternate keyboard can be used). When content can be operated through a keyboard or alternate keyboard, it is operable by people with no vision (who cannot use devices such as mice that require eye-hand coordination) as well as by people who must use alternate keyboards or input devices that act as keyboard emulators. Keyboard emulators include speech input software, sip-and-puff software, on-screen keyboards, scanning software and a variety of assistive technologies and alternate keyboards. Individuals with low vision also may have trouble tracking a pointer and find the use of software much easier (or only possible) if they can control it from the keyboard.
Guideline 2.2 Enough Time
The intent of this Success Criterion is to ensure that users with disabilities are given adequate time to interact with web content whenever possible. People with disabilities such as blindness, low vision, dexterity impairments, and cognitive limitations may require more time to read content or to perform functions such as filling out on-line forms. If web functions are time-dependent, it will be difficult for some users to perform the required action before a time limit occurs. This may render the service inaccessible to them. Providing options to disable time limits, customize the length of time limits, or request more time before a time limit occurs helps those users who require more time than expected to successfully complete tasks. Also, avoid distracting users during their interaction with a web page; such as moving, blinking, scrolling and auto-updating content. Allow users to turn off content updates, except in emergencies. This allows access by people with cognitive limitations or attention disorders by enabling them to focus on the content. It also allows users who are blind or have low vision to keep their “viewing” focus on the content they are currently reading.
Guideline 2.3 Seizures and Physical Reactions
The intent of this Success Criterion is to allow users to access the full content of a site without inducing seizures due to photosensitivity. Individuals who have photosensitive seizure disorders can have a seizure triggered by content that flashes at certain frequencies for more than a few flashes. Some users experience distraction or nausea from animated content. For example, if scrolling a page causes elements to move (other than the essential movement associated with scrolling) it can trigger vestibular disorders. Vestibular (inner ear) disorder reactions include dizziness, nausea and headaches. Another animation that is often non-essential is parallax scrolling. Parallax scrolling occurs when backgrounds move at a different rate to foregrounds. allow users to prevent animation from being displayed on web pages.
Guideline 2.4 Navigable
Provide ways to help users navigate, find content, and determine where they are. A sighted user can ignore repeated content either by focusing on the center of the screen (where main content usually appears) or a mouse user can select a link with a single mouse click rather than encountering every link or form control that comes before the item they want. Likewise, it is important to allow people who navigate sequentially through content with a keyboard more direct access to the primary content of the web page.
Skipping repeated blocks of content, like navigation links, heading graphics, and advertising frames. Help users find content and orient themselves within the website by ensuring that each web page has a descriptive title. Titles identify the current location without requiring users to read or interpret page content. Ensure that when users navigate sequentially through content, they encounter information in an order that is consistent with the meaning of the content and can be operated from the keyboard. This reduces confusion by letting users form a consistent mental model of the content.
Help users understand the purpose of each link so they can decide whether they want to follow the link. Whenever possible, provide link text that identifies the purpose of the link without needing additional context. Assistive technology has the ability to provide users with a list of links that are on the web page. Link text that is as meaningful as possible will aid users who want to choose from this list of links. Also, the intent of this Success Criterion is to help users understand what information is contained in web pages and how that information is organized. When headings are clear and descriptive, users can find the information they seek more easily, and they can understand the relationships between different parts of the content more easily.
Descriptive labels help users identify specific components within the content. Labels and headings do not need to be lengthy. A word, or even a single character, may suffice if it provides an appropriate cue to finding and navigating content. It is important to help a person know which element among multiple elements on the page has the keyboard focus. If there is only one keyboard actionable control on the screen, the success criterion would be met because the visual design presents only one keyboard actionable item. Note that a keyboard focus indicator can take different forms. One common way is a caret within the text field to indicate that the text field has the keyboard focus. Another is a visual change to a button to indicate that the button has the keyboard focus.
Guideline 2.5 Input Modalities
Make it easier for users to operate functionality through various inputs beyond keyboard. The intent of this Success Criterion is to ensure that content can be controlled with a range of pointing devices, abilities, and assistive technologies. Some people cannot perform gestures in a precise manner, or they may use a specialized or adapted input device such as a head pointer, eye-gaze system, or speech-controlled mouse emulator. Some pointing methods lack the capability or accuracy to perform multipoint or path-based gestures. Make it easier for users to prevent accidental or erroneous pointer input. People with various disabilities can inadvertently initiate touch or mouse events with unwanted results.
Also, the intent of this Success Criterion is to ensure that the words which visually label a component are also the words associated with the component programmatically. This helps ensure that people with disabilities can rely on visible labels as a means to interact with the components. Most controls are accompanied by a visible text label. Those same controls have a programmatic name, also known as the Accessible Name. Users typically have a much better experience if the words and characters in the visible label of a control match the accessible name. When these match, speech-input users (using speech recognition applications) can navigate by speaking the visible text labels of components, such as menus, links, and buttons, that appear on the screen. Mismatches between visible labels and programmatic names for controls are even more of an issue for speech-input and text-to-speech users who also have cognitive challenges. Mismatches create an extra cognitive load for speech-input users, who must remember to say a speech command that is different from the visible label they see on a control. It also creates extra cognitive load for a text-to-speech user to absorb and understand speech output that does not match the visible label.