analytics/webcontent/bi/js/gemini/app/util/ScreenReaderUtil.js

'use strict';

/**
 * Licensed Materials - Property of IBM
 * IBM Cognos Products: BI Cloud (C) Copyright IBM Corp. 2014, 2017
 * US Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
 */

define(['jquery', '../../lib/@waca/core-client/js/core-client/ui/core/Class'], function ($, Class) {

	/**
  * This is a utility class to assist with ScreenReader interaction.
  * It provides a standard method to allow callouts on events or other occurances when
  * direct update of the UI is not available to the screen reader.
  * It creates a textbox input that hidden off screen and uses the aria-live attribute
  * to call out the string message.
  *
  * Example Usage:
  *
  *		this.myScreenReader = new ScreenReaderUtil();
  *
  *		someEventHandler: function( event ){
  *
  *			this.myScreenReader.callOut( 'event happened' );
  *		}
  *
  * @class ScreenReaderUtil
  */
	var ScreenReaderUtil = null;
	ScreenReaderUtil = Class.extend({

		INPUTBOX_ID: 'boardScreenReaderInputBox',
		CLEAR_TIMER_DURATION: 500,
		oCallOutClearTimer: null,

		init: function init() {
			ScreenReaderUtil.inherited('init', this, arguments);

			// check to see if the textbox exists and create as necessary
			if ($('#' + this.INPUTBOX_ID).length === 0) {

				// create the screen reader global input box to be used to call out for events etc.
				// position it off screen (must be visible for the screen reader to read it)
				var divScreenReaderCallout = document.createElement('div');
				divScreenReaderCallout.style.width = '0px';
				divScreenReaderCallout.style.height = '0px';
				divScreenReaderCallout.style.overflow = 'hidden';
				divScreenReaderCallout.style.position = 'absolute';
				divScreenReaderCallout.style.top = '-1px';
				divScreenReaderCallout.style.left = '-1px';
				var txtScreenReaderCallout = document.createElement('input');
				txtScreenReaderCallout.type = 'text';
				txtScreenReaderCallout.id = this.INPUTBOX_ID;
				txtScreenReaderCallout.setAttribute('aria-selected', 'false');
				txtScreenReaderCallout.setAttribute('aria-live', 'assertive');
				txtScreenReaderCallout.setAttribute('tabIndex', '-1');
				$(divScreenReaderCallout).append(txtScreenReaderCallout);
				$('body').append(divScreenReaderCallout);
			}
		},

		callOut: function callOut(sMessage) {

			// cancel any existing timer
			if (this.oCallOutClearTimer) {
				clearInterval(this.oCallOutClearTimer);
			}

			// set the value and clear timer
			$('#' + this.INPUTBOX_ID).val(sMessage);
			this.oCallOutClearTimer = setTimeout(function () {
				$('#' + this.INPUTBOX_ID).val('');
			}.bind(this), this.CLEAR_TIMER_DURATION);
		},

		destroy: function destroy() {

			// remove textbox and container
			$('#' + this.INPUTBOX_ID).parent().remove();

			// complete inherited destroy operations
			ScreenReaderUtil.inherited('destroy', this, arguments);
		}

	});
	return ScreenReaderUtil;
});
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