I'm developing an app with Angular and Semantic-UI. The app should be accessible, this means it should be compliant with WCAG 2.0.
To reach this purpose the modals should keep focus within the dialog and prevents users from going outside or move with "tabs" between elements of the page that lays under the modal.
I have found some working examples, like the following:
JQuery dialog: https://jqueryui.com/dialog/#modal-confirmation
dialog HTML 5.1 element: https://demo.agektmr.com/dialog
ARIA modal dialog example:
http://w3c.github.io/aria-practices/examples/dialog-modal/dialog.html
(that I have reproduced on Plunker)
Here is my try to create an accessible modal with Semantic-UI: https://plnkr.co/edit/HjhkZg
As you can see I used the following attributes:
role="dialog"
aria-labelledby="modal-title"
aria-modal="true"
But they don't solve my issue. Do you know any way to make my modal keeping focus and lose it only when user click on cancel/confirm buttons?
There is currently no easy way to achieve this. The inert attribute was proposed to try to solve this problem by making any element with the attribute and all of it's children inaccessible. However, adoption has been slow and only recently did it land in Chrome Canary behind a flag.
Another proposed solution is making a native API that would keep track of the modal stack, essentially making everything not currently the top of the stack inert. I'm not sure the status of the proposal, but it doesn't look like it will be implemented any time soon.
So where does that leave us?
Unfortunately without a good solution. One solution that is popular is to create a query selector of all known focusable elements and then trap focus to the modal by adding a keydown event to the last and first elements in the modal. However, with the rise of web components and shadow DOM, this solution can no longer find all focusable elements.
If you always control all the elements within the dialog (and you're not creating a generic dialog library), then probably the easiest way to go is to add an event listener for keydown on the first and last focusable elements, check if tab or shift tab was used, and then focus the first or last element to trap focus.
If you're creating a generic dialog library, the only thing I have found that works reasonably well is to either use the inert polyfill or make everything outside of the modal have a tabindex=-1.
var nonModalNodes;
function openDialog() {
var modalNodes = Array.from( document.querySelectorAll('dialog *') );
// by only finding elements that do not have tabindex="-1" we ensure we don't
// corrupt the previous state of the element if a modal was already open
nonModalNodes = document.querySelectorAll('body *:not(dialog):not([tabindex="-1"])');
for (var i = 0; i < nonModalNodes.length; i++) {
var node = nonModalNodes[i];
if (!modalNodes.includes(node)) {
// save the previous tabindex state so we can restore it on close
node._prevTabindex = node.getAttribute('tabindex');
node.setAttribute('tabindex', -1);
// tabindex=-1 does not prevent the mouse from focusing the node (which
// would show a focus outline around the element). prevent this by disabling
// outline styles while the modal is open
// #see https://www.sitepoint.com/when-do-elements-take-the-focus/
node.style.outline = 'none';
}
}
}
function closeDialog() {
// close the modal and restore tabindex
if (this.type === 'modal') {
document.body.style.overflow = null;
// restore or remove tabindex from nodes
for (var i = 0; i < nonModalNodes.length; i++) {
var node = nonModalNodes[i];
if (node._prevTabindex) {
node.setAttribute('tabindex', node._prevTabindex);
node._prevTabindex = null;
}
else {
node.removeAttribute('tabindex');
}
node.style.outline = null;
}
}
}
The different "working examples" do not work as expected with a screenreader.
They do not trap the screenreader visual focus inside the modal.
For this to work, you have to :
Set the aria-hidden attribute on any other nodes
disable keyboard focusable elements inside those trees (links using tabindex=-1, controls using disabled, ...)
The jQuery :focusable pseudo selector can be useful to find focusable elements.
add a transparent layer over the page to disable mouse selection.
or you can use the css pointer-events: none property when the browser handles it with non SVG elements, not in IE
This focus-trap plugin is excellent at making sure that focus stays trapped inside of dialogue elements.
It sounds like your problem can be broken down into 2 categories:
focus on dialog box
Add a tabindex of -1 to the main container which is the DOM element that has role="dialog". Set the focus to the container.
wrapping the tab key
I found no other way of doing this except by getting the tabbable elements within the dialog box and listening it on keydown. When I know the element in focus (document.activeElement) is the last one on the list, I make it wrap
"focus" events can be intercepted in the capture phase, so you can listen for them at the document.body level, squelch them before they reach the target element, and redirect focus back to a control in your modal dialog. This example assumes a modal dialog with an input element gets displayed and assigned to the variable currDialog:
document.body.addEventListener("focus", (event) => {
if (currDialog && !currDialog.contains(event.target)) {
event.preventDefault();
event.stopPropagation();
currDialog.querySelector("input").focus();
}
}, {capture: true});
You may also want to contain such a dialog in a fixed-position, clear (or low-opacity) backdrop element that takes up the full screen in order to capture and suppress mouse/pointer events, so that no browser feedback (hover, etc.) occurs that could give the user the impression that the background is active.
Don't use any solution requiring you to look up "tabbable" elements. Instead, use keydown and either click events or a backdrop in an effective manor.
(Angular1)
See Asheesh Kumar's answer at https://stackoverflow.com/a/31292097/1754995 for something similar to what I am going for below.
(Angular2-x, I haven't done Angular1 in a while)
Say you have 3 components: BackdropComponent, ModalComponent (has an input), and AppComponent (has an input, the BackdropComponent, and the ModalComponent). You display BackdropComponent and ModalComponent with the correct z-index, both are currently displayed/visible.
What you need to do is have a general window.keydown event with preventDefault() to stop all tabbing when the backdrop/modal component is displayed. I recommend you put that on a BackdropComponent. Then you need a keydown.tab event with stopPropagation() to handle tabbing for the ModalComponent. Both the window.keydown and keydown.tab could probably be in the ModalComponent but there is purpose in a BackdropComponent further than just modals.
This should prevent clicking and tabbing to the AppComponent input and only click or tab to the ModalComponent input [and browser stuffs] when the modal is shown.
If you don't want to use a backdrop to prevent clicking, you can use use click events similarly to the keydown events described above.
Backdrop Component:
#Component({
selector: 'my-backdrop',
host: {
'tabindex': '-1',
'(window:keydown)': 'preventTabbing($event)'
},
...
})
export class BackdropComponent {
...
private preventTabbing(event: KeyboardEvent) {
if (event.keyCode === 9) { // && backdrop shown?
event.preventDefault();
}
}
...
}
Modal Component:
#Component({
selector: 'my-modal',
host: {
'tabindex': '-1',
'(keydown.tab)': 'onTab($event)'
},
...
})
export class ModalComponent {
...
private onTab(event: KeyboardEvent) {
event.stopPropagation();
}
...
}
Here's my solution. It traps Tab or Shift+Tab as necessary on first/last element of modal dialog (in my case found with role="dialog"). Eligible elements being checked are all visible input controls whose HTML may be input,select,textarea,button.
$(document).on('keydown', function(e) {
var target = e.target;
var shiftPressed = e.shiftKey;
// If TAB key pressed
if (e.keyCode == 9) {
// If inside a Modal dialog (determined by attribute role="dialog")
if ($(target).parents('[role=dialog]').length) {
// Find first or last input element in the dialog parent (depending on whether Shift was pressed).
// Input elements must be visible, and can be Input/Select/Button/Textarea.
var borderElem = shiftPressed ?
$(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').first()
:
$(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').last();
if ($(borderElem).length) {
if ($(target).is($(borderElem))) {
return false;
} else {
return true;
}
}
}
}
return true;
});
we can use the focus trap npm package.
npm i focus-trap
This might help someone who is looking for solution in Angular.
Step 1: Add keydown event on dialog component
#HostListener('document:keydown', ['$event'])
handleTabKeyWInModel(event: any) {
this.sharedService.handleTabKeyWInModel(event, '#modal_id', this.elementRef.nativeElement, 'input,button,select,textarea,a,[tabindex]:not([tabindex="-1"])');
}
This will filters the elements which are preseneted in the Modal dialog.
Step 2: Add common method to handle focus in shared service (or you can add it in your component as well)
handleTabKeyWInModel(e, modelId: string, nativeElement, tagsList: string) {
if (e.keyCode === 9) {
const focusable = nativeElement.querySelector(modelId).querySelectorAll(tagsList);
if (focusable.length) {
const first = focusable[0];
const last = focusable[focusable.length - 1];
const shift = e.shiftKey;
if (shift) {
if (e.target === first) { // shift-tab pressed on first input in dialog
last.focus();
e.preventDefault();
}
} else {
if (e.target === last) { // tab pressed on last input in dialog
first.focus();
e.preventDefault();
}
}
}
}
}
Now this method will take the modal dialog native element and start evaluate on every tab key. Finally we will filter the event on first and last so that we can focus on appropriate elements (on first after last element tab click and on last shift+tab event on first element).
Happy Coding.. :)
I used one of the methods suggested by Steven Lambert, namely, listening to keydown events and intercepting "tab" and "shift+tab" keys. Here's my sample code (Angular 5):
import { Directive, ElementRef, Attribute, HostListener, OnInit } from '#angular/core';
/**
* This directive allows to override default tab order for page controls.
* Particularly useful for working around the modal dialog TAB issue
* (when tab key allows to move focus outside of dialog).
*
* Usage: add "custom-taborder" and "tab-next='next_control'"/"tab-prev='prev_control'" attributes
* to the first and last controls of the dialog.
*
* For example, the first control is <input type="text" name="ctlName">
* and the last one is <button type="submit" name="btnOk">
*
* You should modify the above declarations as follows:
* <input type="text" name="ctlName" custom-taborder tab-prev="btnOk">
* <button type="submit" name="btnOk" custom-taborder tab-next="ctlName">
*/
#Directive({
selector: '[custom-taborder]'
})
export class CustomTabOrderDirective {
private elem: HTMLInputElement;
private nextElemName: string;
private prevElemName: string;
private nextElem: HTMLElement;
private prevElem: HTMLElement;
constructor(
private elemRef: ElementRef
, #Attribute('tab-next') public tabNext: string
, #Attribute('tab-prev') public tabPrev: string
) {
this.elem = this.elemRef.nativeElement;
this.nextElemName = tabNext;
this.prevElemName = tabPrev;
}
ngOnInit() {
if (this.nextElemName) {
var elems = document.getElementsByName(this.nextElemName);
if (elems && elems.length && elems.length > 0)
this.nextElem = elems[0];
}
if (this.prevElemName) {
var elems = document.getElementsByName(this.prevElemName);
if (elems && elems.length && elems.length > 0)
this.prevElem = elems[0];
}
}
#HostListener('keydown', ['$event'])
onKeyDown(event: KeyboardEvent) {
if (event.key !== "Tab")
return;
if (!event.shiftKey && this.nextElem) {
this.nextElem.focus();
event.preventDefault();
}
if (event.shiftKey && this.prevElem) {
this.prevElem.focus();
event.preventDefault();
}
}
}
To use this directive, just import it to your module and add to Declarations section.
I've been successful using Angular Material's A11yModule.
Using your favorite package manager install these to packages into your Angular app.
**"#angular/material": "^10.1.2"**
**"#angular/cdk": "^10.1.2"**
In your Angular module where you import the Angular Material modules add this:
**import {A11yModule} from '#angular/cdk/a11y';**
In your component HTML apply the cdkTrapFocus directive to any parent element, example: div, form, etc.
Run the app, tabbing will now be contained within the decorated parent element.
For jquery users:
Assign role="dialog" to your modal
Find first and last interactive element inside the dialog modal.
Check if current target is one of them(depending on shift key is
pressed or not).
If target element is one of first or last interactive element of the
dialog, return false
Working code sample:
//on keydown inside dialog
$('.modal[role=dialog]').on('keydown', e => {
let target = e.target;
let shiftPressed = e.shiftKey;
// If TAB is pressed
if (e.keyCode === 9) {
// Find first and last element in the ,modal-dialog parent.
// Elements must be interactive i.e. visible, and can be Input/Select/Button/Textarea.
let first = $(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').first();
let last = $(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').last();
let borderElem = shiftPressed ? first : last //border element on the basis of shift key pressed
if ($(borderElem).length) {
return !$(target).is($(borderElem)); //if target is border element , return false
}
}
return true;
});
I read through most of the answers, while the package focus-trap seems like a good option. #BenVida shared a very simple VanillaJS solution here in another Stack Overflow post.
Here is the code:
const container=document.querySelector("_selector_for_the_container_")
//optional: needed only if the container element is not focusable already
container.setAttribute("tabindex","0")
container.addEventListener("focusout", (ev)=>{
if (!container.contains(ev.relatedTarget)) container.focus()
})
I'm using instantsearch.js and a combination of widgets to display my search results (pretty much modeled exactly after the demos).
I need to set some initial values for facets so certain items are filtered on by default. How do I do this? I know the AlgoliaSearchHelper (helper) object has a method toggleRefinement that should allow me to do this but I can't seem to access this helper prior to calling search.start() which does the initial query.
Any advice or insight on how to set some default refinements would be appreciated. Thanks.
Update: This isn't a duplicate - my issue seems to have been with the instantsearch.widget.toggle. It looks like this widget sets default values behind the scenes before the initial search. I've adjusted my code to not use this widget and to just set the searchParameters.tagFilters property instead. It was the toggle widget throwing things off for me as I couldn't figure out how to override its default filtering.
The easiest way to add initial filters to your instantsearch.js instance is to use an extra custom widget:
var search = instantsearch({
appId: 'YourApplicationID',
apiKey: 'YourSearchOnlyAPIKey',
indexName: 'YourIndexName'
});
search.addWidget(
instantsearch.widgets.searchBox({
container: '#search-box',
placeholder: 'Search for FIXME...'
})
);
search.addWidget(
instantsearch.widgets.hits({
container: '#hits-container',
templates: {
item: 'Hit {{objectID}}: FIXME'
}
})
);
// setup initial filters
search.addWidget({
init: function(options) {
// use options.helper (https://github.com/algolia/algoliasearch-helper-js) to initialize the search with custom filters & parameters
options.helper.addFacetRefinement('MyFacet', 'my value');
}
});
search.start();
This is what worked for us:
search.addWidgets([{
init: function(options) {
options.helper.toggleRefinement('attribute', 'value');
}
}]);
My issue seems to have been with the instantsearch.widget.toggle. It looks like this widget sets default values behind the scenes before the initial search. I've adjusted my code to not use this widget and to just set the searchParameters.tagFilters property instead. It was the toggle widget throwing things off for me as I couldn't figure out how to override its default filtering.
You are indeed right, under the hood the toggle widget uses the off value if provided:
if (userValues.off === undefined) {
return;
}
// Add filtering on the 'off' value if set
let isRefined = state.isFacetRefined(attributeName, userValues.on);
if (!isRefined) {
helper.addFacetRefinement(attributeName, userValues.off);
}
To avoid this incomprehension from other users, there is now a PR on instantsearch.js with the following update:
Note that if you provide an "off" option, it will be refined at initialization.
I upgraded the kendo library to the 2014Q1 framework which had a few nice features that they were adding, however when I did that it broke any widget (grid, tabStrip, select lists, etc.) from rendering at all. I tracked it down to the layout/view not being able to activate the widget without being wrapped in a setTimeout set to 0. Am I missing something key here or did I build this thing in an invalid way?
http://jsfiddle.net/upmFf/
The basic idea of the problem I am having is below (remove the comments and it works):
var router = new kendo.Router();
var mainLayout = new kendo.Layout($('#mainLayout').html());
var view = new kendo.View('sample', {
wrap: false,
model: kendo.observable({}),
init: function() {
// setTimeout(function(){
$("#datepicker").kendoDatePicker();
// }, 0);
}
});
mainLayout.render('#container');
router.route('/', function() {
mainLayout.showIn('#app', view);
});
router.start();
Admittedly, I don't fully understand it, but hope this helps.
Basically when you try to init the #datepicker, the view elements have not been inserted into the DOM yet. You can put a breakpoint inside the init function, when it hits, check the DOM and you will see that the #app is an empty div, and #datepicker does not exist yet (at least not on the DOM).
kendo.Layout.showIn seems to need to exit in order for the view to finish rendering, but when it initializes the view's elements, it thinks the render is done and init is triggered incorrectly ahead of time. The setTimeout works because it runs the kendoDatePicker initialization asynch, the view is able to finish rendering before the timeout function.
Workarounds...
Trigger the view rendering from the view object itself:
var view = new kendo.View('sample', {
init: function() {
$("#datepicker").kendoDatePicker();
}
});
router.route('/', function() {
view.render('#app');
});
Select and find the datepicker from the view object itself:
var view = new kendo.View('sample', {
init: function() {
view.element.find("#datepicker").kendoDatePicker();
}
});
router.route('/', function() {
mainLayout.showIn('#app', view);
});
Near the bottom of this thread is where I got the idea for the 2nd option. Maybe someone else can come around and give a better explanation of whats going on.
According to document, I can make custom drop effect by overriding
Widget.dropEffect_(boolean)
However, I cannot make a widget display different drop effect according to dragged widget, because there is no reference of the dragged widget available.
My question is :
How do I make a drop effect that can changes according to dragged widget ?
You can override getDrop_ function to log the current dragged widget,
e.g.,
zk.afterLoad("zul", function () {
var _wgt = {};
zk.override(zk.Widget.prototype, _wgt, {
getDrop_: function (dragged) {
zk.Widget.currentDraggedInstance = dragged;
return _wgt.getDrop_.apply(this, arguments);
}
});
});
see the sample at zkfiddle for more information
custom drop effect
I would like to be able to move around (on the greyed-out background, by dragging and dropping) the modal form that is provided by Bootstrap 2. Can anyone tell me what the best practice for achieving this is?
The bootstrap doesn't come with any dragging and dropping functionality by default, but you can add a little jQuery UI spice into the mix to get the effect you're looking for. For example, using the draggable interaction from the framework you can target your modal ID to allow it to be dragged around within the modal backdrop.
Try this:
JS
$("#myModal").draggable({
handle: ".modal-header"
});
Demo, edit here.
Update: bootstrap3 demo
Whatever draggable option you go for, you might want to turn off the *-transition properties for .modal.fade in bootstrap’s CSS file, or at least write some JS that temporarily disables them during dragging. Otherwise, the modal doesn’t drag exactly as you would expect.
You can use a little script likes this.
simplified from Draggable without jQuery UI
(function ($) {
$.fn.drags = function (opt) {
opt = $.extend({
handle: "",
cursor: "move"
}, opt);
var $selected = this;
var $elements = (opt.handle === "") ? this : this.find(opt.handle);
$elements.css('cursor', opt.cursor).on("mousedown", function (e) {
var pos_y = $selected.offset().top - e.pageY,
pos_x = $selected.offset().left - e.pageX;
$(document).on("mousemove", function (e) {
$selected.offset({
top: e.pageY + pos_y,
left: e.pageX + pos_x
});
}).on("mouseup", function () {
$(this).off("mousemove"); // Unbind events from document
});
e.preventDefault(); // disable selection
});
return this;
};
})(jQuery);
example : $("#someDlg").modal().drags({handle:".modal-header"});
Building on previous answers utilizing jQuery UI, this, included once, will apply to all your modals and keep the modal on screen, so users don't accidentally move the header off screen so they can no longer access the handle. Also sets the cursor to 'move' for better discoverability.
$(document).on('shown.bs.modal', function(evt) {
let $modal = $(evt.target);
$modal.find('.modal-content').draggable({
handle: ".modal-header",
containment: $modal
});
$modal.find('.modal-header').css('cursor', 'move')
});
evt.target is the .modal which is the translucent overlay behind the actual .modal-content.
jquery UI is large and can conflict with bootstrap.
An alternative is DragDrop.js: http://kbjr.github.io/DragDrop/index.html
DragDrop.bind($('#myModal')[0], {
anchor: $('#myModal .modal-header')
});
You still have to deal with transitions, as #user535673 suggests. I just remove the fade class from my dialog.