Tabindex html что это

rgbeast

Что означает на практике, что tabindex станет применим ко всем элементам? Правильно ли я понимаю, что можно будет задать tabindex у div, tr, td, br? Изменят ли дефолтное поведение браузеры?

1234ru

AlexNZ

1234ru

AlexNZ

Т.е. вы спросили у пользователя его согласие, как это принято в параноидальной MS Windows (R).

М-да. Но тут есть подводный камень. Дело в том, что такой полезный код работает только при кнопке (как в первом примере), а вот во втором примере случится следующее: FireFox и Opera покажут вопрос юзеру, но данные отправят при любом ответе, а IE так и вовсе не покажет вопроса. 🙂 Возрадуйтесь!

— это только для JavaScript’а? Нет.
Вы можете обработать события возникающие в тэге другими средствами. Например IE может обрабатывать события HTML на языке visualbasic (но только IE). Вы можете написать плагин к браузеру используя его API. Еще есть язык Java, да и ActionScript (из Flash) теперь способен на многое. Это не весь список.
Более того, мы ведь говорим об HTML, а не о браузерах, так что можно написать свою программу поддерживающую стандарт HTML, со своим макроязыком. Короче не стоит замыкаться 🙂

Ну вот, хотел отделаться только первым предложением. 🙂

В Вашем комментарии много ошибочных утверждений. Начнем по порядку.

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Атрибут tabindex

Добавить элемент в список табуляции

Попробуйте использовать для HTML-элемента button или там, где это необходимо.

Удалить элемент из списка табуляции

Элемент будет удален из списка табуляции, но все равно его можно будет выделить.

Пользовательский порядок табуляции (не рекомендуется)

Положительные значения вставляют элемент в список табуляции в соответствии со значением. Элементы без предпочтений (т. e. tabindex = «0» или собственные элементы, такие как button или a ) будут добавляться после остальных.

Использовать положительные значения не рекомендуются, так как они нарушают ожидаемое поведение табуляции и могут сбивать с толку людей, которые применяют на устройства чтения с экрана. Попробуйте создать естественный порядок, изменив структуру DOM.

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Using tabindex

The default tab order provided by the DOM position of native elements is convenient, but there are times when you’ll want to modify the tab order, and physically moving elements in the HTML isn’t always an optimal, or even a feasible, solution. For these cases you can use the tabindex HTML attribute to explicitly set an element’s tab position.

tabindex=»0″ : Inserts an element into the natural tab order. The element can be focused by pressing the Tab key, and the element can be focused by calling its focus() method

tabindex=»-1″ : Removes an element from the natural tab order, but the element can still be focused by calling its focus() method

tabindex=»5″ : Any tabindex greater than 0 jumps the element to the front of the natural tab order. If there are multiple elements with a tabindex greater than 0, the tab order starts from the lowest value that is greater than zero and works its way up. Using a tabindex greater than 0 is considered an anti-pattern.

Managing focus at the page level

Here’s a scenario where tabindex is not only useful, but necessary. You might be building a robust single page with different content sections, not all of which are simultaneously visible. In this kind of page, clicking a navigation link might change the visible content without doing a page refresh.

Managing focus in components

Managing focus when you change something on the page is important, but sometimes you need to manage focus at the control level — for example, if you’re building a custom component.

Consider the native select element. It can receive basic focus but, once there, you can use the arrow keys to expose additional functionality (the selectable options). If you were building a custom select element, you would want to expose these same kinds of behaviors so that users who rely primarily on the keyboard could still interact with your control.

Knowing which keyboard behaviors to implement can be difficult, but there is a helpful document you can refer to. The Accessible Rich Internet Applications (ARIA) Authoring Practices guide lists types of components and what kinds of keyboard actions they support. We will cover ARIA in more detail later, but for now let’s use the guide to help us add keyboard support to a new component.

Perhaps you’re working on some new Custom Elements that resemble a set of radio buttons, but with your unique take on appearance and behavior.

To determine what kind of keyboard support they need, you would check the ARIA Authoring Practices guide. Section 2 contains a list of design patterns, and in that list is a characteristics table for radio groups, the existing component that most closely matches your new element.

As you can see in the table, one of the common keyboard behaviors that should be supported is the up/down/left/right arrow keys. To add this behavior to the new component, we’ll use a technique called roving tabindex.

When the user reaches the last (or first, depending on the direction they’re moving the focus) child, you will loop around and focus the first (or last) child again.

You can give the completed example a try down below. Inspect the element in the DevTools to observe the tabindex moving from one radio to the next.

Modals and keyboard traps

Sometimes when you’re managing focus you can get into a situation you can’t get out of. Consider an autocomplete widget that tries to manage focus and captures the tab behavior, but prevents the user from leaving it until it’s complete. This is called a keyboard trap, and it can be very frustrating for the user. Section 2.1.2 of the Web AIM checklist addresses this issue, stating that keyboard focus should never be locked or trapped at one particular page element. The user should be able to navigate to and from all page elements using only the keyboard.

Oddly, there are times when this behavior is actually desirable, like in a modal window. Normally, when the modal is displayed, you don’t want the user to access the content behind it. You might add an overlay to cover the page visually, but that doesn’t stop keyboard focus from accidentally traveling outside the modal.

In instances like this you can implement a temporary keyboard trap to ensure that you trap focus only while the modal is displayed and then restore focus to the previously-focused item when the modal is closed.

There are some proposals on how to make this easier for developers, including the element, but they don’t yet have widespread browser support.

Consider a modal dialog represented by a div that contains a few elements, and another div that represents a background overlay. Let’s walk through the basic steps needed to implement a temporary keyboard trap in this situation.

This procedure gives you a usable, non-frustrating modal window that everyone can use effectively.

For more details, you can examine this sample code, and view a live example from a completed page.

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bitsofcode

Save Article for Offline Nov 29, 2018 html

tabindex is a global attribute that can be applied to most HTML elements with content. It controls two things:

Focus order

To understand how the tabindex attribute works, we first need to understand how focus is controlled on a page.

There are six 1 HTML elements which, by default, are focusable:

By default, only these elements can be brought into focus either with a user tabbing around the page with a keyboard or via the focus() method in Javascript.

Without any intervention, calling focus() on any other element simply will not work.

The order in which these elements are placed in the source HTML document controls the order in which they become focusable when navigating with a keyboard.

Although this default behaviour covers most of the interaction we would need, there may be cases where we want to remove, add, or re-arrange items in the focus order. This is where the tabindex attribute becomes handy.

How to use tabindex

The tabindex attribute can be applied to almost any element, whether it is by default focusable or not. The value of the attribute must be a valid integer and can either be negative, positive, or exactly zero.

Negative tabindex values

Click me to start, then press the «tab» key
I’ll be in focus first
I won’t be in focus 🙁
I’ll be in focus last

A tabindex value of zero

A tabindex equals to exactly zero will place the element in the default focus order, determined by its position in the source HTML. It can be applied to elements that are not typically focusable, and will add them to the natural focus order as if they were.

Click me to start, then press the «tab» key
I’ll be in focus first

Positive tabindex values

Finally, a positive tabindex will place the element in the focus order, but it’s position will be determined by the specific number, starting from 1 and going up. Elements with a positive tabindex will also be placed in front of elements that don’t have a tabindex attribute.

To test this out, click on the URL bar of your browser, then hit tab. You’ll see that the first two focusable items on this page are the buttons below, even though they are in the middle of the source HTML.

I’m the first focusable item on the page
I’m the second

Programmatic focus and tabindex

Besides controlling which elements can be focusable via the keyboard and focus order, the tabindex attribute also controls which elements can be focusable via Javascript.

Adding the tabindex attribute to an element, regardless of the value, makes it focusable via Javascript. This means that we can make elements that are previously unfocusable to be focusable via Javascript, without also making them able to be focused via the user tabbing around using their keyboard.

If we were to navigate using the keyboard, we will see that it is not able to grab focus.

Click me to start, then press the «tab» key

However, we can bring focus to it using the focus() method.

Click me to focus the DIV

Next, we’ll see how this difference between tab and programmatic focus makes the tabindex attribute useful.

When to use tabindex

The tabindex attribute can be very useful, but has potentially destructive consequences if not used correctly. Each category of tabindex value should be used in different circumstances.

When to use a negative tabindex value

As we have covered, a negative tabindex value will remove the element from tab focus, but can add elements to programmatic focus.

A great example of when this is useful is modals. Modal containers are typically unfocusable elements like

When to use a tabindex value of zero

A tabindex of zero is typically used either to add focus back to elements that it was programatically removed from.

When to use a positive tabindex value

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