Day: September 19, 2020

Introduction

In the beginning, the Web was just text, and it was really quite boring. Fortunately, it wasn’t too long before the ability to embed images (and other more interesting types of content) inside web pages was added. There are other types of multimedia to consider, but it is logical to start with the humble <img> element, used to embed a simple image in a webpage. In this unit we’ll look at how to use it in depth, including the basics, annotating it with captions using <figure>.

How do we put an image on a webpage?

In order to put a simple image on a webpage, we use the <img> element. This is a void element (meaning that it has no text content or closing tag) that requires a minimum of one attribute to be useful: src (sometimes spoken as its full title, source). The src attribute contains a path pointing to the image you want to embed in the page, which can be a relative or absolute URL, in the same way as href attribute values in <a> elements.

So for example, if your image is called dinosaur.jpg and it sits in the same directory as your HTML page, you could embed the image like so:

<img src="dinosaur.jpg" />

If the image was in an images subdirectory, which was inside the same directory as the HTML page (which Google recommends for SEO/indexing purposes), then you’d embed it like this:

<img src="images/dinosaur.jpg" />

Search engines also read image filenames and count them towards SEO. Therefore, you should give your image a descriptive filename; dinosaur.jpg is better than img835.jpg.

You also could embed the image using its absolute URL, for example:

<img src="https://www.example.com/images/dinosaur.jpg" />
...
<img src="https://developer.mozilla.org/static/img/favicon144.png" />

Alternative text

The next attribute we’ll look at is alt. Its value is supposed to be a textual description of the image, to be used by search engines, and also in situations where the image cannot be seen/displayed or takes a long time to render because of a slow internet connection. Keep in mind that an alt attribute’s value should clearly and concisely describe the image’s content. For example, our above code could be modified like so:

<img src="images/dinosaur.jpg"
     alt="The head and torso of a dinosaur skeleton;
          it has a large head with long sharp teeth" />
...
<img src="https://developer.mozilla.org/static/img/favicon144.png"
     alt="MDN logo" />

The easiest way to test your alt text is to purposely misspell your filename. If for example our image name was spelled dinosoooor.jpg, the browser wouldn’t display the image, and would display the alt text instead.

So, why would you ever see or need alt text? It can come in handy for a number of reasons:

• The user is visually impaired, and is using a screen reader to read the web out to them. In fact, having alt text available to describe images is useful to most users.
• As described above, the spelling of the file or path name might be wrong.
• The browser doesn’t support the image type. Some people still use text-only browsers, such as Lynx, which displays the alt text of images.
• You may want to provide text for search engines to utilize; for example, search engines can match alt text with search queries.
• Users have turned off images to reduce data transfer volume and distractions. This may be especially common on mobile phones, and in countries where bandwidth is limited or expensive.

What exactly should you write inside your alt attribute? It depends on why the image is there in the first place. In other words, what you lose if your image doesn’t show up:

• Content. If your image provides significant information, provide the same information in a brief alt text – or even better, in the main text which everybody can see. Don’t write redundant alt text. How annoying would it be for a sighted user if all paragraphs were written twice in the main content? If the image is described adequately by the main text body, you can just use alt="".
• Link. If you put an image inside <a> tags, to turn an image into a link, you still must provide accessible link text. In such cases you may, either, write it inside the same <a> element, or inside the image’s alt attribute – whichever works best in your case.
• Text. You should not put your text into images. If your main heading needs a drop shadow, for example, use CSS for that rather than putting the text into an image. However, If you really can’t avoid doing this, you should supply the text inside the alt attribute.

Essentially, the key is to deliver a usable experience, even when the images can’t be seen. This ensures all users are not missing any of the content. Try turning off images in your browser and see how things look. You’ll soon realize how helpful alt text is if the image cannot be seen.

Width and height

You can use the width and height attributes to specify the width and height of your image. We could do this:

<img src="images/dinosaur.jpg"
     alt="The head and torso of a dinosaur skeleton;
          it has a large head with long sharp teeth"
     width="400"
     height="340" />

However, you shouldn’t alter the size of your images using always HTML attributes. If you set the image size too big, you’ll end up with images that look grainy, fuzzy, or too small, and wasting bandwidth downloading an image that is not fitting the user’s needs. The image may also end up looking distorted, if you don’t maintain the correct aspect ratio. You should use an image editor to put your image at the correct size before putting it on your webpage, but if you do need to alter an image’s size, you should use CSS instead.

Image titles

As with links, you can also add title attributes to images, to provide further supporting information if needed. In our example, we could do this:

<img src="images/dinosaur.jpg"
     alt="The head and torso of a dinosaur skeleton;
          it has a large head with long sharp teeth"
     title="A T-Rex on display in the Manchester University Museum" />

This gives us a tooltip on mouse hover, just like link titles. However, it should not be used as a replacement of the text inside the alt attribute. The title has a number of accessibility problems, mainly based around the fact that screen reader support is very unpredictable and most browsers won’t show it unless you are hovering with a mouse (so e.g. no access to keyboard users).

Proposed exercise: Embedding images

Create a web page to display several images. You have to use the basic <img> tag and the src attribute to point to the URL of each individual image. Por example, you can use images like these ones:

https://developer.mozilla.org/static/img/favicon144.png

https://raw.githubusercontent.com/mdn/learning-area/master/html/multimedia-and-embedding/images-in-html/dinosaur_small.jpg

https://validator.w3.org/images/w3c.png

You must also add some alt text to each image, and check that they work by misspelling the image URL’s. And finally experiment with different values of width and height to see what the effect is.

Image link

This example builds upon the previous ones, showing how to turn the image into a link. To do so, nest the <img> tag inside the <a>. You should use the alternative text to describe the resource the link is pointing to, as if you were using a text link instead:

<a href="https://developer.mozilla.org">
  <img src="https://developer.mozilla.org/static/img/favicon144.png"
       alt="Visit the MDN site" />
</a>

Proposed exercise: Top ten pages

Create a web page showing an ordered list (<ol>) of the top ten web pages you like. You must use images to create links to each page, and set the height attribute to the same value for all the images so that all of them are the same height. For example:

<ol>
  <li>
    <a href="https://developer.mozilla.org">
      <img src="https://developer.mozilla.org/static/img/favicon144.png" 
           alt="MDN site" height="100" />
    </a>
  </li>
  <li>
    <a href="https://validator.w3.org/">
      <img src="https://validator.w3.org/images/w3c.png" 
           alt="Markup Validation Service" height="100" />
    </a>
  </li>
  ...
</ol>

Annotating images with figures and figure captions

Speaking of captions, there are a number of ways that you could add a caption to go with your image. For example, there would be nothing to stop you from doing this:

<div class="figure">
  <img src="images/dinosaur.jpg"
       alt="The head and torso of a dinosaur skeleton;
            it has a large head with long sharp teeth"
       width="400"
       height="340">

  <p>A T-Rex on display in the Manchester University Museum.</p>
</div>

This is ok, since it contains the content you need, and can be nicely styled using CSS. But there is a problem here: there is nothing that semantically links the image to its caption, which can cause problems for screen readers. For example, when you have 50 images and captions, which caption goes with which image?

A better solution is to use the HTML5 <figure> and <figcaption> elements. These are created for exactly this purpose: to provide a semantic container for figures, and to clearly link the figure to the caption. Our above example could be rewritten like this:

<figure>
  <img src="images/dinosaur.jpg"
       alt="The head and torso of a dinosaur skeleton;
            it has a large head with long sharp teeth"
       width="400"
       height="340">

  <figcaption>A T-Rex on display in the Manchester University Museum.</figcaption>
</figure>

The <figcaption> element tells browsers, and assistive technology that the caption describes the other content of the <figure> element. From an accessibility viewpoint, captions and alt text have distinct roles. Captions benefit even people who can see the image, whereas alt text provides the same functionality as an absent image. Therefore, captions and alt text shouldn’t just say the same thing, because they both appear when the image is gone. Try turning images off in your browser and see how it looks.

Also keep in mind that a figure could be made of several images, a code snippet, audio, video, equations, a table, or something else. We will go through this in another unit.

Proposed exercise: Figures with captions

Create a web page to display several images you like, using the <figure> element, and add a caption to each one using the <figcaption> element, as it is done in the example below:

<figure>
  <img src="https://developer.mozilla.org/static/img/favicon144.png"
       alt="Mozilla developer website">
  <figcaption>MDN Logo</figcaption>
</figure>

<figure>
  <img src="https://validator.w3.org/images/w3c.png"
       alt="W3C Validator">
  <figcaption>W3C Logo</figcaption>
</figure>

...

Proposed exercise: Top ten films

Create a new web page showing an ordered list (<ol>) of the top ten films you like. In this case you must use figures with captions to create links to each page. Set the height attribute to the same value for all the images so that all of them are the same height. For example:

<ol>
  <li>
    <a href="https://en.wikipedia.org/wiki/Steve_Jobs_(film)">
      <figure>
        <img src="https://upload.wikimedia.org/wikipedia/commons/4/49/SteveJobsMacbookAir.JPG" 
             alt="Steve Jobs and Macbook Air" height="100" />
        <figcaption>Steve jobs</figcaption>
      </figure>
    </a>
  </li>
  <li>
    <a href="https://en.wikipedia.org/wiki/2001:_A_Space_Odyssey_(film)">
      <figure>
        <img src="https://upload.wikimedia.org/wikipedia/en/0/09/2001child2.JPG" 
             alt="Baby, space and Earth" height="100" />
        <figcaption>2001: A Space Odyssey</figcaption>
      </figure>
    </a>
  </li>
  ...
</ol>

Quiz

Test your skills with this quiz about images and some other concepts related to this unit.

Introduction

Now let’s turn our attention to lists. Lists are everywhere in life —from your shopping list to the list of directions you subconsciously follow to get to your house every day, to the lists of instructions you are following in these tutorials! Lists are everywhere on the web, too, and we’ve got three different types to worry about.

Unordered lists (<ul> element)

Unordered lists are used to mark up lists of items for which the order of the items doesn’t matter. Let’s take a shopping list in plain text as an example:

milk
eggs
bread
hummus

In HTML, unordered lists can be displayed like this:

• milk
• eggs
• bread
• hummus

To get that result and display the bulleted list, every unordered list starts off with a <ul> element (this wraps around all the list items). The last step is to wrap each list item in a <li> (list item) element:

<ul>
  <li>milk</li>
  <li>eggs</li>
  <li>bread</li>
  <li>hummus</li>
</ul>

Ordered lists (<ol> element)

Ordered lists are lists in which the order of the items does matter. Let’s take a set of directions in plain text as an example:

Drive to the end of the road
Turn right
Go straight across the first two roundabouts
Turn left at the third roundabout
The school is on your right, 300 meters up the road

In HTML, ordered lists can be displayed like this:

1. Drive to the end of the road
2. Turn right
3. Go straight across the first two roundabouts
4. Turn left at the third roundabout
5. The school is on your right, 300 meters up the road

The markup structure is the same as for unordered lists, except that you have to wrap the list items in an <ol> element, rather than <ul>:

<ol>
  <li>Drive to the end of the road</li>
  <li>Turn right</li>
  <li>Go straight across the first two roundabouts</li>
  <li>Turn left at the third roundabout</li>
  <li>The school is on your right, 300 meters up the road</li>
</ol>

Proposed exercise: Hummus recipe

At this point you have all the information you need to mark up a recipe page example. Using the text below, create a new file and use the proper tags to improve the format of the hummus recipe:

Note: You must use <h1> for the main title, <h2> for the other titles, <p> for the paragraphs, <ul> for the ingredients, and <ol> for the instructions.

Quick hummus recipe

This recipe makes quick, tasty hummus, with no messing. It has been adapted from a number of different recipes that I have read over the years.

Hummus is a delicious thick paste used heavily in Greek and Middle Eastern dishes. It is very tasty with salad, grilled meats and pitta breads.

Ingredients

1 can (400g) of chick peas (garbanzo beans)
175g of tahini
6 sundried tomatoes
Half a red pepper
A pinch of cayenne pepper
1 clove of garlic
A dash of olive oil

Instructions

Remove the skin from the garlic, and chop coarsely
Remove all the seeds and stalk from the pepper, and chop coarsely
Add all the ingredients into a food processor
Process all the ingredients into a paste
If you want a coarse "chunky" hummus, process it for a short time
If you want a smooth hummus, process it for a longer time

For a different flavour, you could try blending in a small measure of lemon and coriander, chili pepper, lime and chipotle, harissa and mint, or spinach and feta cheese. Experiment and see what works for you.

Storage

Refrigerate the finished hummus in a sealed container. You should be able to use it for about a week after you've made it. If it starts to become fizzy, you should definitely discard it.

Hummus is suitable for freezing; you should thaw it and use it within a couple of months.

Nesting lists

It is perfectly ok to nest one list inside another one. You might want to have for example a sublist sitting below a top-level bullet:

• first item
• second item
  • second item first subitem
  • second item second subitem
  • second item third subitem
• third item

<ul>
  <li>first item</li>
  <li>second item     
  <!-- Look, the closing </li> tag is not placed here! -->
    <ul>
      <li>second item first subitem</li>
      <li>second item second subitem</li>
      <li>second item third subitem</li>
    </ul>
  <!-- Here is the closing </li> tag -->
  </li>
  <li>third item</li>
</ul>

And you also might want to have an ordered list inside an unordered list:

• first item
• second item
  1. second item first subitem
  2. second item second subitem
  3. second item third subitem
• third item

<ul>
  <li>first item</li>
  <li>second item
  <!-- Look, the closing </li> tag is not placed here! -->
    <ol>
      <li>second item first subitem</li>
      <li>second item second subitem</li>
      <li>second item third subitem</li>
    </ol>
  <!-- Here is the closing </li> tag -->
  </li>
  <li>third item</li>
</ul>

Let’s take a look now at the second list from our recipe example, and we will understand how useful nested lists can be:

<ol>
  <li>Remove the skin from the garlic, and chop coarsely.</li>
  <li>Remove all the seeds and stalk from the pepper, and chop coarsely.</li>
  <li>Add all the ingredients into a food processor.</li>
  <li>Process all the ingredients into a paste.</li>
  <li>If you want a coarse "chunky" hummus, process it for a short time.</li>
  <li>If you want a smooth hummus, process it for a longer time.</li>
</ol>

Since the last two bullets are very closely related to the one before them (they read like sub-instructions or choices that fit below that bullet), it might make sense to nest them inside their own unordered list and put that list inside the current fourth bullet. This would look like so:

<ol>
  <li>Remove the skin from the garlic, and chop coarsely.</li>
  <li>Remove all the seeds and stalk from the pepper, and chop coarsely.</li>
  <li>Add all the ingredients into a food processor.</li>
  <li>Process all the ingredients into a paste.
    <ul>
      <li>If you want a coarse "chunky" hummus, process it for a short time.</li>
      <li>If you want a smooth hummus, process it for a longer time.</li>
    </ul>
  </li>
</ol>

Proposed exercise: Hummus recipe

Using the previous proposed exercise of the hummus recipe, update the second list to use nested items to get the following result:

1. Remove the skin from the garlic, and chop coarsely.
2. Remove all the seeds and stalk from the pepper, and chop coarsely.
3. Add all the ingredients into a food processor.
4. Process all the ingredients into a paste.
   • If you want a coarse “chunky” hummus, process it for a short time.
   • If you want a smooth hummus, process it for a longer time.

Proposed exercise: Shopping list

Write your own shopping list, with at least 25 products. You must use types and subtypes, by wrapping the items in nested lists as the following example:

• Bread
• Milk
• Coffee
• Tea
  • Black tea
  • Green tea
• Fruit
  • Oranges
  • Apples

<ul>
  <li>Bread</li>
  <li>Milk</li>
  <li>Coffee</li>
  <li>Tea
    <ul>
      <li>Black tea</li>
      <li>Green tea</li>
    </ul>
  </li>
  <li>Fruit
    <ul>
      <li>Oranges</li>
      <li>Apples</li>
    </ul>
  </li>
</ul>

Proposed exercise: Things to do

Create a new file containing a list of things to do, with at least 25 items. You must use nested lists mixing things and instructions, for example, by inserting ordered lists inside an unordered list, more or less like the example below:

• Feed cat
  1. Wash the bowl
  2. Open cat food
  3. Deliver it to the cat
• Wash car
  1. Vacuum interior
  2. Wash exterior
  3. Wax exterior
• Grocery shopping
  1. Plan meals
  2. Clean out fridge
  3. Make list
  4. Go to the store

<ul>
   <li>Feed cat
     <ol>
       <li>Wash the bowl</li>
       <li>Open cat food</li>
       <li>Deliver it to the cat</li>
     </ol>
   </li>
   <li>Wash car
     <ol>
       <li>Vacuum interior</li>
       <li>Wash exterior</li>
       <li>Wax exterior</li>
     </ol>
   </li>
   <li>Grocery shopping
     <ol>
       <li>Plan meals</li>
       <li>Clean out fridge</li>
       <li>Make list</li>
       <li>Go to the store</li>
     </ol>
   </li>
</ul>

Description lists (<dl> element)

We have walked through how to mark up basic lists. Now we are going to mention the third type of list, which you will occasionally come across: description lists. The purpose of these lists is to mark up a set of items and their associated descriptions, such as terms and definitions, or questions and answers. Let’s look at an example of a set of terms and definitions:

soliloquy

In drama, where a character speaks to themselves, representing their inner thoughts or feelings and in the process relaying them to the audience (but not to other characters.)

monologue

In drama, where a character speaks their thoughts out loud to share them with the audience and any other characters present.

aside

In drama, where a character shares a comment only with the audience for humorous or dramatic effect. This is usually a feeling, thought or piece of additional background information

Description lists use a different wrapper than the other list types, since they are delimited by the <dl> tag. In addition each term is wrapped in a <dt> (description term) element, and each description is wrapped in a <dd> (description definition) element. Let’s finish marking up our example:

<dl>
  <dt>soliloquy</dt>
  <dd>In drama, where a character speaks to themselves, representing their inner thoughts or feelings and in the process relaying them to the audience (but not to other characters.)</dd>

  <dt>monologue</dt>
  <dd>In drama, where a character speaks their thoughts out loud to share them with the audience and any other characters present.</dd>

  <dt>aside</dt>
  <dd>In drama, where a character shares a comment only with the audience for humorous or dramatic effect. This is usually a feeling, thought, or piece of additional background information.</dd>
</dl>

The browser will display description lists with the descriptions indented somewhat from the terms. Also note that it is permitted to have a single term with multiple descriptions, for example:

<dl>
  <dt>aside</dt>
  <dd>In drama, where a character shares a comment only with the audience for humorous or dramatic effect. This is usually a feeling, thought, or piece of additional background information.</dd>
  <dd>In writing, a section of content that is related to the current topic, but doesn't fit directly into the main flow of content so is presented nearby (often in a box off to the side.)</dd>
</dl>

Proposed exercise: Coffee, Tea and Chocolate

It’s time to try your hand at description lists. Create a new file and add elements to the raw text below so that it appears as a description list:

Coffee

Coffee is a brewed beverage with a distinct aroma and flavor prepared from the roasted seeds of the Coffea plant.

Tea

Tea is an aromatic beverage commonly prepared by pouring hot or boiling water over cured leaves of the tea plant.

Hot chocolate

Hot chocolate (also known as hot cocoa) is a heated beverage typically consisting of shaved chocolate, melted chocolate or cocoa powder, heated milk or water, and sugar.

Proposed exercise: Bacon, Eggs and Coffee

Create a new file with the text below and add elements to the raw text so that it appears as a description list. You could try using your own terms and descriptions if you like:

Bacon

Cured meat prepared from a pig.

Eggs

Common food and one of the most versatile ingredients used in cooking.

Coffee

The drink that gets the world running in the morning.
A light brown color.

Proposed exercise: Computer hardware

Write a definition list to explain the meaning of the following terms: Central processing unit, monitor, mouse, keyboard, graphics card, sound card, speakers and motherboard.

Quiz

Test your skills with this quiz about text formatting and some other concepts related to this unit.