Button

Overview

In most circumstances, using a native HTML <button> or <input type="submit"> element is a better choice than creating a custom ARIA button, but there are use cases where an ARIA button can be appropriate, such as when styling a standard <button> is too difficult in the range of target browsers under certain circumstances, or when retrofitting legacy markup that could be problematic to convert to standard <button> elements.

Turn on a screen reader to experience this example in action.

Primary Button (ARIA)

Secondary Button (ARIA)

Initial HTML Markup

<p>
<button class="deque-button" id="deque-button-primary-html">Primary Button (HTML)</button>
<span role="button" class="deque-button deque-button-aria" id="deque-button-primary-aria">Primary Button (ARIA)</span>
</p>
<p>
<button class="deque-button deque-button-secondary" id="deque-button-secondary-html" type="button">Secondary Button (HTML)</button>
<span role="button" class="deque-button deque-button-secondary deque-button-aria" id="deque-button-secondary-aria">Secondary Button (ARIA)</span>
</p>

JavaScript

Required: The complete JavaScript file (for all patterns in the library): deque-patterns.min.js

Key parts of the JavaScript file

Note: The code below is functional only in the context of the complete JavaScript file.

In the @button section:


      function bindElementToInputs(element, behavior) {
        if (element.tagName.toUpperCase() !== 'BUTTON') {
          (0, _keyboardUtils.onElementSpace)(element, function (e) {
            e.preventDefault();
            e.stopPropagation();

            behavior(e);
          });

          (0, _keyboardUtils.onElementEnter)(element, function (e) {
            e.preventDefault();
            e.stopPropagation();

            behavior(e);
          });
        }

        element.addEventListener('click', behavior);
      }

      function assignRoleIfNecessary(element) {
        if (element.tagName.toLowerCase() !== 'button') {
          element.setAttribute('role', 'button');
          element.setAttribute('tabindex', '0');
        }
      }

      function initializeIcon(element) {
        var icon = document.createElement('span');
        icon.setAttribute('aria-hidden', true);
        icon.classList.add('pressed-on-icon');
        element.insertBefore(icon, element.firstChild);
      }

      function initializeButton(element, behavior) {
        assignRoleIfNecessary(element);
        bindElementToInputs(element, behavior);
      }

      function initializeToggleButton(element, toggleFunction) {
        var initialState = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : false;

        assignRoleIfNecessary(element);
        element.setAttribute('aria-pressed', initialState);
        initializeIcon(element);

        if (!toggleFunction) {
          throw new Error('You must provide a toggle function to a toggle button. It should return \'true\' when the button should have a \'pressed\' state, and \'false\' otherwise.');
        }

        function toggle(e) {
          var toggledOn = toggleFunction(e);
          element.setAttribute('aria-pressed', toggledOn ? 'true' : 'false');
        }

        bindElementToInputs(element, toggle);
      }

In the @keyboardUtils section:


      var KEYS = exports.KEYS = {
        BACKSPACE: 8,
        TAB: 9,
        ENTER: 13,
        SHIFT: 16,
        CTRL: 17,
        ALT: 18,
        ESCAPE: 27,
        SPACE: 32,
        LEFT: 37,
        RIGHT: 39,
        UP: 38,
        DOWN: 40,
        F10: 121,
        HOME: 36,
        END: 35,
        PAGE_UP: 33,
        PAGE_DOWN: 34
      };

      function bindElementToEventValue(element, eventName, testValue, handler) {
        function localHandler(e) {
          if (e.which === testValue) {
            handler(e);
          }
        }

        element.addEventListener(eventName, localHandler);
        return function () {
          element.removeEventListener(eventName, localHandler);
        };
      }

      function bindElementToKeypressValue(element, testValue, handler) {
        return bindElementToEventValue(element, 'keypress', testValue, handler);
      }

      function bindElementToKeydownValue(element, testValue, handler) {
        return bindElementToEventValue(element, 'keydown', testValue, handler);
      }

      function onElementEnter(element, handler) {
        return bindElementToKeydownValue(element, KEYS.ENTER, handler);
      }

      function onElementEscape(element, handler) {
        return bindElementToKeydownValue(element, KEYS.ESCAPE, handler);
      }

      function onElementSpace(element, handler) {
        return bindElementToKeypressValue(element, KEYS.SPACE, handler);
      }

      function onElementLeft(element, handler) {
        return bindElementToKeydownValue(element, KEYS.LEFT, handler);
      }

      function onElementRight(element, handler) {
        return bindElementToKeydownValue(element, KEYS.RIGHT, handler);
      }

      function onElementUp(element, handler) {
        return bindElementToKeydownValue(element, KEYS.UP, handler);
      }

      function onElementDown(element, handler) {
        return bindElementToKeydownValue(element, KEYS.DOWN, handler);
      }

      function onElementHome(element, handler) {
        return bindElementToKeydownValue(element, KEYS.HOME, handler);
      }

      function onElementEnd(element, handler) {
        return bindElementToKeydownValue(element, KEYS.END, handler);
      }

      function onElementPageUp(element, handler) {
        return bindElementToKeydownValue(element, KEYS.PAGE_UP, handler);
      }

      function onElementPageDown(element, handler) {
        return bindElementToKeydownValue(element, KEYS.PAGE_DOWN, handler);
      }

      function onElementF10(element, handler) {
        return bindElementToKeydownValue(element, KEYS.F10, handler);
      }

      function isAlphaNumeric(charCode) {
        return charCode >= 48 && charCode <= 90 /* numbers, uppercase letters */
          || charCode >= 97 && charCode <= 122 /* lowercase letters */;
      }

      function onElementCharacter(element, handler) {
        function localHandler(e) {
          var charCode = e.which;
          if (isAlphaNumeric(charCode)) {
            handler(e);
          }
        }

        element.addEventListener('keypress', localHandler);
        return function () {
          element.removeEventListener('keypress', localHandler);
        };
      }

      function trapEnter(element) {
        onElementEnter(element, function (e) {
          e.stopPropagation();
          e.preventDefault();
        });
      }

Required: Initialization JavaScript (with functionality specific to individual widget instances):

/* Specify which buttons */
var primaryHtml = document.getElementById('deque-button-primary-html');
var primaryAria = document.getElementById('deque-button-primary-aria');
var secondaryHtml = document.getElementById('deque-button-secondary-html');
var secondaryAria = document.getElementById('deque-button-secondary-aria');

/* Define the functionality for the buttons */
function primaryHtmlHandler() {
  alert('You clicked the primary HTML button');
}

function primaryAriaHandler() {
  alert('You clicked the primary ARIA button');
}

function secondaryHtmlHandler() {
  alert('You clicked the secondary HTML button');
}

function secondaryAriaHandler() {
  alert('You clicked the secondary ARIA button');
}

/* Initialize buttons */
deque.button.initializeButton(primaryHtml, primaryHtmlHandler);
deque.button.initializeButton(primaryAria, primaryAriaHandler);
deque.button.initializeButton(secondaryHtml, secondaryHtmlHandler);
deque.button.initializeButton(secondaryAria, secondaryAriaHandler);

CSS

Required: The complete CSS file (for all patterns in the library): deque-patterns.min.css

Key styles within the CSS file (other styles may also be necessary):


button.deque-button,
input[type='submit'].deque-button,
input[type='image'].deque-button,
input[type='reset'].deque-button,
[role='button'].deque-button {
  cursor: default;
  margin: 0;
  font-size: 15px;
  max-width: 374px;
  min-width: 120px;
  display: inline-block;
  padding: 9px 12px 10px;
  border: solid 1px #006cc1;
  border-radius: 0;
  overflow: hidden;
  line-height: 1;
  text-align: center;
  white-space: nowrap;
  vertical-align: bottom;
  outline: none;
  background: #006cc1;
  color: #ffffff;
  font-family: inherit;
}
button.deque-button:hover,
input[type='submit'].deque-button:hover,
input[type='image'].deque-button:hover,
input[type='reset'].deque-button:hover,
[role='button'].deque-button:hover {
  background-color: #fdf6e7;
  color: #004c87;
  border-color: #990000;
  margin: 0;
}
button.deque-button.deque-button-secondary,
input[type='submit'].deque-button.deque-button-secondary,
input[type='image'].deque-button.deque-button-secondary,
input[type='reset'].deque-button.deque-button-secondary,
[role='button'].deque-button.deque-button-secondary {
  background-color: #e6e6e6;
  color: #000000;
  border: 1px solid #006cc1;
}
button.deque-button.deque-button-secondary:hover,
input[type='submit'].deque-button.deque-button-secondary:hover,
input[type='image'].deque-button.deque-button-secondary:hover,
input[type='reset'].deque-button.deque-button-secondary:hover,
[role='button'].deque-button.deque-button-secondary:hover {
  background-color: #fdf6e7;
  color: #004c87;
  border-color: #990000;
  border: 2px solid red;
}
button.deque-button:focus,
input[type='submit'].deque-button:focus,
input[type='image'].deque-button:focus,
input[type='reset'].deque-button:focus,
[role='button'].deque-button:focus {
  outline: 1px dashed #000000;
}

Implementation Instructions

Step 1: Add Dependencies

Add deque-patterns.min.css in the <head> of the document.

<link rel="stylesheet" type="text/css" href="deque-patterns.min.css">

Add a script link to deque-patterns.min.js to the bottom of the page.

<script type="text/javascript" src="deque-patterns.min.js"></script>

Step 2: Add HTML

Wrap the HTML in <div class="deque-wrapper">, for styling purposes.
Identify the elements to be used as buttons with a unique ID. The element can be a <span> or any other element.

Note:

If your element is already a <button>, the JavaScript simply wires it up to the handler but if it's a non-button element, role="button" is set and bindings are created for space bar and enter key activation in addition to click.

Step 3: Add JavaScript

Call deque.button.initializeButton with:

The element you want to behave like a button
A function you want executed when the button is activated (there is no default behavior; you have to write the function).