Tables: rowspan and colspan

Posted by toonmaybe

Tables may have seemed complicated enough in the HTML Beginner Tutorial. It can be quite difficult to visualize a two-dimensional grid from one-dimensional lines of code.

Well, it gets trickier. All thanks to the rowspan and colspan attributes. Those bastards.

The following code is similar to that in the Tables page of the HTML Beginner Tutorial:


<table>
    <tr>
        <th>Column 1 heading</th>
        <th>Column 2 heading</th>
        <th>Column 3 heading</th>
    </tr>
    <tr>
        <td>Row 2, cell 1</td>
        <td colspan="2">Row 2, cell 2, also spanning Row 2, cell 3</td>
    </tr>
    <tr>
        <td rowspan="2">Row 3, cell 1, also spanning Row 4, cell 1</td>
        <td>Row 3, cell 2</td>
        <td>Row 3, cell 3</td>
    </tr>
    <tr>
        <td>Row 4, cell 2</td>
        <td>Row 4, cell 3</td>
    </tr>
</table>

Header cells

The first difference is that the td tags of the first row have been replaced with th tags. Whereas a td is a standard data cell, th is a header cell. As with td elements, these must be enclosed inside tr elements.

Spanning columns and rows

colspan and rowspan attributes have also been used in some of the td tags. If you look at this code in a browser, you will see that on the second row there are now two cells instead of three, the second cell spanning the second and third column. The colspan attribute, which means “column span” will span the cell over the number of cells that is specified. This means, in this example, that there is no need for a third td element – two cells are merged into one.

The rowspan attribute is similar to colspan, except, obviously, it will span across rows rather than columns. Again, the cells that it spans should be removed. In this example, because it spans over the fourth row, there is only two cells in that row.

As with the simpler 3×4, 12-cell table, the numbers on these tables with merged cells should also add up. Although there are only 10 cells in this example, there are 2 spans.

Putting It All Together

Posted by toonmaybe

The following code incorporates all of the methods that have been explained in the previous pages:


<!DOCTYPE html>

<html>

<head>

    <title>My first web page</title>

    <!-- This is a comment, by the way -->

</head>

<body>

<h1>My first web page</h1>

<h2>What this is</h2>
<p>A simple page put together using HTML. <em>I said a simple page put together using HTML.</em> A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML. A simple page put together using HTML.</p>

<h2>Why this is</h2>
<ul>
    <li>To learn HTML</li>
    <li>
        To show off
        <ol>
            <li>To my boss</li>
            <li>To my friends</li>
            <li>To my cat</li>
            <li>To the little talking duck in my brain</li>
        </ol>
    </li>
    <li>Because I have fallen in love with my computer and want to give her some HTML loving.</li>
</ul>

<h2>Where to find the tutorial</h2>
<p><a href="http://www.htmldog.com"><img src="http://www.htmldog.com/badge1.gif" width="120" height="90" alt="HTML Dog"></a></p>

<h3>Some random table</h3>
<table>
    <tr>
        <td>Row 1, cell 1</td>
        <td>Row 1, cell 2</td>
        <td>Row 1, cell 3</td>
    </tr>
    <tr>
        <td>Row 2, cell 1</td>
        <td>Row 2, cell 2</td>
        <td>Row 2, cell 3</td>
    </tr>
    <tr>
        <td>Row 3, cell 1</td>
        <td>Row 3, cell 2</td>
        <td>Row 3, cell 3</td>
    </tr>
    <tr>
        <td>Row 4, cell 1</td>
        <td>Row 4, cell 2</td>
        <td>Row 4, cell 3</td>
    </tr>
</table>

<h3>Some random form</h3>
<p><strong>Note:</strong> It looks the part, but won't do a damned thing.</p>

<form action="somescript.php" method="post">

<p>Name:</p>
<p><input name="name" value="Your name"></p>

<p>Comments: </p>
<p><textarea rows="10" cols="20" name="comments">Your comments</textarea></p>

<p>Are you:</p>
<p><input type="radio" name="areyou" value="male"> Male</p>
<p><input type="radio" name="areyou" value="female"> Female</p>
<p><input type="radio" name="areyou" value="hermaphrodite"> An hermaphrodite</p>
<p><input type="radio" name="areyou" value="asexual" checked> Asexual</p>

<p><input type="submit"></p>

</form>

</body>

</html>

Tables

Posted by toonmaybe

There are a number of tags used in tables, and to fully get to grips with how they work is probably the most difficult area of this HTML Beginner Tutorial.

Copy the following code into the body of your document and then we will go through what each tag is doing:


<table>
    <tr>
        <td>Row 1, cell 1</td>
        <td>Row 1, cell 2</td>
        <td>Row 1, cell 3</td>
    </tr>
    <tr>
        <td>Row 2, cell 1</td>
        <td>Row 2, cell 2</td>
        <td>Row 2, cell 3</td>
    </tr>
    <tr>
        <td>Row 3, cell 1</td>
        <td>Row 3, cell 2</td>
        <td>Row 3, cell 3</td>
    </tr>
    <tr>
        <td>Row 4, cell 1</td>
        <td>Row 4, cell 2</td>
        <td>Row 4, cell 3</td>
    </tr>
</table>

The table element defines the table.

The tr element defines a table row.

The td element defines a data cell. These must be enclosed in tr tags, as shown above.

If you imagine a 3×4 table, which is 12 cells, there should be four tr elements to define the rows and three td elements within each of the rows, making a total of 12 td elements.

Images

Posted by toonmaybe

The img tag is used to put an image in an HTML document and it looks like this:


<img src="http://www.htmldog.com/badge1.gif" width="120" height="90" alt="HTML Dog">

The src attribute tells the browser where to find the image. Like the a tag, this can be absolute, as the above example demonstrates, but is usually relative. For example, if you create your own image and save it as “alienpie.jpg” in a directory called “images” then the code would be <img src="images/alienpie.jpg"...

The width and height attributes are necessary because if they are excluded, the browser will tend to calculate the size as the image loads, instead of when the page loads, which means that the layout of the document may jump around while the page is loading.

The alt attribute is the alternative description. This is an accessibility consideration, providing meaningful information for users who are unable to see the image (if they are visually impaired, for example).

Note that, like the br tag, because the img element does not enclose any content, no closing tag is required.

The construction of images for the web is a little outside of the remit of this website, but it is worth noting a few things…

The most commonly used file formats used for images are JPEGs, GIFs, and PNGs. They are compressed formats, and have very different uses.

A JPEG (pronounced “jay-peg”) uses a mathematical algorithm to compress the image and will distort the original slightly. The lower the compression, the higher the file size, but the clearer the image.

JPEGs are typically used for images such as photographs.

A GIF (pronounced “jif”) can have no more than 256 colors, but they maintain the colors of the original image. The lower the number of colors you have in the image, the lower the file size will be. GIFs also allow any pixel in the image to be transparent.

GIFs are typically used for images with solid colors, such as icons or logos.

A PNG (pronounced “ping”) replicates colors, much like a GIF, but allows 16 million colors as well as alpha transparency (that is, an area could be 50% transparent).

PNGs are typically used for versatile images in more complex designs BUT they are not fully supported by some older browsers.

The web is forever getting faster and faster but you obviously want your web pages to download as quickly as possible. Using super-high resolution images isn’t doing your or your user’s bandwidth (or patience) any favors. Image compression is a great tool and you need to strike a balance between image quality and image size. Most modern image manipulation programs allow you to compress images and the best way to figure out what is best suited for yourself is trial and error.

Links

Posted by toonmaybe

An anchor tag (a) is used to define a link, but you also need to add something to the anchor tag – the destination of the link.

Add this to your document:


<!DOCTYPE html>

<html>

<head>
    <title>My first web page</title>
</head>

<body>

    <h1>My first web page</h1>

    <h2>What this is</h2>
    <p>A simple page put together using HTML</p>

    <h2>Why this is</h2>
    <p>To learn HTML</p>

    <h2>Where to find the tutorial</h2>
    <p><a href="http://www.htmldog.com">HTML Dog</a></p>

</body>

</html>

The destination of the link is defined in the href attribute of the tag. The link can be absolute, such as “http://www.htmldog.com”, or it can be relative to the current page.

So if, for example, you had another file called “flyingmoss.html” in the same directory then the line of code would simply be <a href="flyingmoss.html">The miracle of moss in flight</a> or something like this.

A link does not have to link to another HTML file, it can link to any file anywhere on the web.

Lists

Posted by toonmaybe

Unordered lists and ordered lists work the same way, except that the former is used for non-sequential lists with list items usually preceded by bullets and the latter is for sequential lists, which are normally represented by incremental numbers.

The ul tag is used to define unordered lists and the ol tag is used to define ordered lists. Inside the lists, the li tag is used to define each list item.

Change your code to the following:


<!DOCTYPE html>

<html>

<head>
    <title>My first web page</title>
</head>

<body>
    <h1>My first web page</h1>

    <h2>What this is</h2>
    <p>A simple page put together using HTML</p>

    <h2>Why this is</h2>
    <ul>
        <li>To learn HTML</li>
        <li>To show off</li>
        <li>Because I've fallen in love with my computer and want to give her some HTML loving.</li>
    </ul>

</body>

</html>

If you look at this in your browser, you will see a bulleted list. Simply change the ul tags to ol and you will see that the list will become numbered.

Lists can also be included in lists to form a structured hierarchy of items.

Replace the above list code with the following:


<ul>
    <li>To learn HTML</li>
    <li>
        To show off
        <ol>
            <li>To my boss</li>
            <li>To my friends</li>
            <li>To my cat</li>
            <li>To the little talking duck in my brain</li>
        </ol>
    </li>
    <li>Because I've fallen in love with my computer and want to give her some HTML loving.</li>
</ul>

Paragraphs

Posted by toonmaybe

Go back to your text editor and add another line to your page:


<!DOCTYPE html>
<html>
<head>
    <title>My first web page</title>
</head>
<body>
    This is my first web page
    How exciting
</body>
</html>

Look at the document in your browser.

You might have expected your document to appear as you typed it, on two lines, but instead you should see something like this:

This is my first web page How exciting.

This is because web browsers don’t usually take any notice of what line your code is on. It also doesn’t take any notice of spaces (you would get the same result if you typed “This is my first web page How exciting”).

If you want text to appear on different lines or, rather, if you intend there to be two distinct blocks of text (because, remember, HTML is about meaning, not presentation), you need to explicitly state that.

Change your two lines of content so that they look like this:

Page Titles

Posted by toonmaybe

To add a title to your page, change your code so that it looks like this:


<!DOCTYPE html>
<html>
<head>
    <title>My first web page</title>
</head>
<body>
    This is my first web page
</body>
</html>

We have added two new elements here, that start with the head tag and the title tag (and see how both of these close).

The head element (that which starts with the <head> opening tag and ends with the </head> closing tag) appears before the body element (starting with <body> and ending with </body>) and contains information about the page. The information in the head element does not appear in the browser window.

We will see later on that other elements can appear inside the head element, but the most important of them is the title element.

If you look at this document in the browser (save and reload as before), you will see that “My first web page” will appear on a tab or the title bar of the window (not the actual canvas area). The text that you put in between the title tags has become the title of the document (surprise!). If you were to add this page to your “favorites” (or “bookmarks”, depending on your browser), you would see that the title is also used there.

Tags, Attributes, and Elements

Posted by toonmaybe

ส่วนหัวเรื่องเอกสารเว็บ (Head Section)

Posted by toonmaybe

Head Section เป็นส่วนที่ใช้อธิบายเกี่ยวกับข้อมูลเฉพาะของหน้าเว็บนั้นๆ เช่น ชื่อเรื่องของหน้าเว็บ (Title), ชื่อผู้จัดทำเว็บ (Author),

คีย์เวิร์ดสำหรับการค้นหา (Keyword) โดยมี Tag สำคัญ คือ

nHead Section เป็นส่วนที่ใช้อธิบายเกี่ยวกับข้อมูลเฉพาะของหน้าเว็บนั้นๆ เช่น ชื่อเรื่องของหน้าเว็บ (Title), ชื่อผู้จัดทำเว็บ (Author),

คีย์เวิร์ดสำหรับการค้นหา(Keyword) โดยมี Tag สำคัญ คือ

nข้อความที่ใช้เป็น TITLE ไม่ควรพิมพ์เกิน 64 ตัวอักษร, ไม่ต้องใส่ลักษณะพิเศษ เช่น ตัวหนา, เอียง หรือสี

และควรใช้เฉพาะภาษาอังกฤษที่มีความหมายครอบคลุมถึงเนื้อหาของเอกสารเว็บ หรือมีลักษณะเป็นคำสำคัญในการค้นหา (Keyword)

nการแสดงผลจาก Tag TITLE บนเบราเซอร์จะปรากฏข้อความที่กำกับด้วย Tag TITLE ในส่วนบนสุดของกรอบหน้าต่าง (ใน Title Bar ของ Window นั่นเอง)

nTag META จะไม่ปรากฏผลบนเบราเซอร์ แต่จะเป็นส่วนสำคัญ ในการทำคลังบัญชีเว็บ สำหรับผู้ให้บริการสืบค้นเว็บ (Search Engine)

และค่าอื่นๆ ของการแปลความหมาย

nการพิมพ์ชุดคำสั่ง HTML สามารถพิมพ์ได้ทั้งตัวพิมพ์เล็ก ตัวพิมพ์ใหญ่ หรือผสม การย่อหน้า เว้นบรรทัด หรือช่องว่าง

สามารถกระทำได้อิสระ โปรแกรมเบราเซอร์จะไม่สนใจเกี่ยวกับระยะเว้นบรรทัดหรือย่อหน้า หรือช่องว่าง

<HEAD>

<TITLE>เรียนรู้ HTML</TITLE>

</HEAD>

ผลที่ได้คือ

การสร้างเว็บเพจhtml

A great WordPress.com site

Tables: rowspan and colspan

Header cells

Spanning columns and rows

Putting It All Together

Tables

Images

Links

Lists

Paragraphs

Page Titles

Tags, Attributes, and Elements

Tags

ส่วนหัวเรื่องเอกสารเว็บ (Head Section)