Images


Images in HTML are inline elements that can be placed within a paragraph. To add an image, use the <img> tag along with the src attribute to specify the location of the image.

<img src="/static/img/code.jpg">

You may use JavaScript to trigger an event when an image finished loading.

<img src="/static/img/code.jpg" onload="alert('image loaded')">

Resizing the image can be done using the width and height attributes of an image, or alternatively by using CSS:

<img src="/static/img/code.jpg" width="100">

<img src="/static/img/code.jpg" style="width: 100px">

Having an "alt" attribute set for the image is useful for when an image could not load or when you want to add a tooltip description that will be displayed when hovering on top of an image.

<img src="/static/img/code.jpg" style="width: 100px" alt="A picture of some code">

Image Types

There are three main types of image formats which you should be using.

  • Lossless formats - useful for when you need pixel-perfect graphics, for example for logos. The most common format is PNG. PNG also supports alpha transparency, meaning that you can use any background you want and overlay the image on top of that background.
  • Lossy formats - useful for displaying rich images. Using a lossless format such as PNG would be an order of magnitude larger if used in such images. The most common format used in this category is JPG.
  • Animated formats - useful for showing short animated images. The most common format is GIF, although it is a very old yet widely supported format, with many inherent drawbacks, such as a 256 color limit on each frame, and bad compression.

Using the CSS float attribute with images

Images can be set to float nearby text so they would blend with the text better. Notice the use of the clear CSS attribute - which directs the browser to break the floating effect after the first paragraph.

<img src="/static/img/lab.png" style="float: left;">

<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore 
magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo 
consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. 
Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

<p class="clear: both">Second paragraph</p>

Exercise

This page does not have an exercise yet. You are welcome to contribute one by sending me a pull request:

https://github.com/ronreiter/interactive-tutorials