为什么不在HTML中使用表格布局呢?

在HTML中，表格不应该用于布局，这似乎是普遍的观点。

Why?

我从来没有(老实说，很少)看到过支持这一点的有力论据。通常的答案是:

It's good to separate content from layoutBut this is a fallacious argument; Cliche Thinking. I guess it's true that using the table element for layout has little to do with tabular data. So what? Does my boss care? Do my users care?Perhaps me or my fellow developers who have to maintain a web page care... Is a table less maintainable? I think using a table is easier than using divs and CSS.By the way... why is using a div or a span good separation of content from layout and a table not? Getting a good layout with only divs often requires a lot of nested divs. Readability of the codeI think it's the other way around. Most people understand HTML, few understand CSS. It's better for SEO not to use tablesWhy? Can anybody show some evidence that it is? Or a statement from Google that tables are discouraged from an SEO perspective? Tables are slower.An extra tbody element has to be inserted. This is peanuts for modern web browsers. Show me some benchmarks where the use of a table significantly slows down a page. A layout overhaul is easier without tables, see css Zen Garden.Most web sites that need an upgrade need new content (HTML) as well. Scenarios where a new version of a web site only needs a new CSS file are not very likely. Zen Garden is a nice web site, but a bit theoretical. Not to mention its misuse of CSS.

我对使用divs + CSS而不是表的良好参数非常感兴趣。

当前回答

In the past, screen readers and other accessibility software had a difficult time handling tables in an efficient fashion. To some extent, this became handled in screen readers by the reader switching between a "table" mode and a "layout" mode based on what it saw inside the table. This was often wrong, and so the users had to manually switch the mode when navigating through tables. In any case, the large, often highly nested tables were, and to a large extent, are still very difficult to navigate through using a screen reader.

The same is true when divs or other block-level elements are used to recreate tables and are highly nested. The purpose of divs is to be used as a fomating and layout element, and as such, are intended used to hold similar information, and lay it out on the screen for visual users. When a screen reader encounters a page, it often ignores any layout information, both CSS based, as well as html attribute based(This isn't true for all screen readers, but for the most popular ones, like JAWS, Windows Eyes, and Orca for Linux it is).

为此，表格式数据，也就是逻辑上有意义的在二维或多维维度中排序的数据，具有某种标题，最好放在表中，并使用div来管理页面上内容的布局。(另一种思考“表格数据”的方式是尝试以图表形式绘制它……如果你不能，它可能不是最好的表示在一个表中)

Finally, with a table-based layout, in order to achieve a fine-grained control of the position of elements on the page, highly nested tables are often used. This has two effects: 1.) Increased code size for each page - Since navigation and common structure is often done with the tables, the same code is sent over the network for each request, whereas a div/css based layout pulls the css file over once, and then uses less wordy divs. 2.) Highly nested tables take much longer for the client's browser to render, leading to slightly slower load times.

在这两种情况下，“最后一英里”带宽的增加，以及更快的个人电脑缓解了这些因素，但它们仍然是许多网站存在的问题。

With all of this in mind, as others have said, tables are easier, because they are more grid-oriented, allowing for less thought. If the site in question is not expected to be around long, or will not be maintained, it might make sense to do what is easiest, because it might be the most cost effective. However, if the anticipated userbase might include a substantial portion of handicapped individuals, or if the site will be maintained by others for a long time, spending the time up front to do things in a concise, accessible way may payoff more in the end.

2008-10-15 03:29:37

其他回答

内容和布局之间的分离也使它更容易为您的网站生成打印机友好的布局或不同的皮肤(样式)，而不必创建不同的html文件。有些浏览器(如Firefox)甚至支持从视图菜单中选择样式表。

而且我确实认为保持无表格布局更容易。你不需要担心行span, colspan等等。您只需创建一些容器div并将内容放置在需要的位置。也就是说，我认为它也更有可读性(<div id="sidebar"> vs <tr><td>…</td><td>…<td>sidebar</td></tr>)。

这只是一个你必须学会的小“技巧”(一旦你掌握了这个技巧，我认为它会更容易，更有意义)。

2008-09-17 13:29:08

下面是来自最近项目的一段html:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <title>{DYNAMIC(TITLE)}</title>
    <meta http-equiv="content-type" content="text/html;charset=utf-8" />
    <meta http-equiv="Content-Style-Type" content="text/css" />
    <link rel="stylesheet" type="text/css" href="./styles/base.css" />
</head>
<body>
    <div id="header">
        <h1><!-- Page title --></h1>
        <ol id="navigation">
            <!-- Navigation items -->
        </ol>
        <div class="clearfix"></div>
    </div>
    <div id="sidebar">
        <!-- Sidebar content -->
    </div>
    <!-- Page content -->
    <p id="footer"><!-- Footer content --></p>
</body>
</html>

这是与基于表格的布局相同的代码。

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <title>{DYNAMIC(TITLE)}</title>
    <meta http-equiv="content-type" content="text/html;charset=utf-8" />
    <meta http-equiv="Content-Style-Type" content="text/css" />
    <link rel="stylesheet" type="text/css" href="./styles/base.css" />
</head>
<body>
    <table cellspacing="0">
        <tr>
            <td><!-- Page Title --></td>
            <td>
                <table>
                    <tr>
                        <td>Navitem</td>
                        <td>Navitem</td>
                    </tr>
                </table>
            </td>
        </tr>
    </table>

    <table>
        <tr>
            <td><!-- Page content --></td>
            <td><!-- Sidebar content --></td>
        </tr>
        <tr>
            <td colspan="2">Footer</td>
        </tr>
    </table>
</body>
</html>

我在基于表格的布局中看到的唯一干净的地方是我对缩进的过度热情。我确信内容部分将有另外两个嵌入式表。

另一件需要考虑的事情是:文件大小。我发现基于表格的布局通常是CSS布局的两倍大。在我们的高速宽带上，这不是一个大问题，但在那些拨号调制解调器上。

2008-09-18 10:10:56

一般来说，表并不比CSS更容易或更易于维护。然而，在一些特定的布局问题中，表确实是最简单和最灵活的解决方案。

在表示标记和CSS支持相同类型的设计的情况下，CSS显然是更可取的，没有人会认为字体标记比在CSS中指定排版更好，因为CSS提供了与字体标记相同的功能，但以一种更干净的方式。

The issue with tables, however, is basically that the table-layout model in CSS is not supported in Microsoft Internet Explorer. Tables and CSS are therefore not equivalent in power. The missing part is the grid-like behavior of tables, where the edges of cells align both vertically and horizontally, while cells still expand to contain their content. This behavior is not easy to achieve in pure CSS without hardcoding some dimensions, which makes the design rigid and brittle (as long as we have to support Internet Explorer - in other browsers this is easliy achieved by using display:table-cell).

因此，这并不是一个表或CSS更可取的问题，而是一个认识到使用表可以使布局更灵活的具体情况的问题。

不使用表的最重要原因是可访问性。Web内容可访问性指南http://www.w3.org/TR/WCAG10/建议不要使用表格进行布局。如果您担心可访问性(在某些情况下，您可能有法律义务这样做)，即使表更简单，也应该使用CSS。请注意，您总是可以用CSS创建与表相同的布局，这可能只是需要更多的工作。

2008-09-18 09:43:50

当您需要确保元素在布局中保持特定的物理关系时，请使用表格。对于数据，表格通常是最适合使用的布局元素，因为您不希望列以超出预期的方式包装，从而混淆了关联。

也有人可能会说，必须保持特定关系的非数据元素也应该呈现在表中。

灵活的css布局非常适合于移动设备、大屏幕、打印和其他显示类型的内容，但有时，内容必须以非常特定的方式显示，如果这要求屏幕阅读器无法轻松访问它，那么它可能是非常合理的。

2008-09-17 16:12:35

使用DIV，您可以轻松地进行切换。例如，你可以这样做:

Menu | Content

Content | Menu

Menu
----
Content

在CSS中更改它很容易，而在HTML中则不然。你也可以提供几种风格(右手，左手，专为小屏幕)。

在CSS中，您还可以将菜单隐藏在用于打印的特殊样式表中。

另一个好处是，你的内容在代码中总是按照相同的顺序(菜单在前，内容在后)，即使在视觉上它是以其他方式呈现的。

2008-09-18 09:15:53

为什么不在HTML中使用表格布局呢?

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