Tuesday, August 4, 2015

How to be a software engineer 18

HTML Lists

Unordered lists and ordered lists are commonly used in HTML:

Unordered List

  • The first item
  • The second item
  • The third item
  • The fourth item

Ordered List

  1. The first item
  2. The second item
  3. The third item
  4. The fourth item


Unordered HTML Lists

An unordered list starts with the <ul> tag. Each list item starts with the <li> tag.
The list items will be marked with bullets (small black circles):

Example

<ul>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>


Unordered HTML Lists - The Style Attribute

A style attribute can be added to an unordered list, to define the style of the marker:
Style Description
list-style-type:disc The list items will be marked with bullets (default)
list-style-type:circle The list items will be marked with circles
list-style-type:square The list items will be marked with squares
list-style-type:none The list items will not be marked

Disc:

<ul style="list-style-type:disc">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Circle:

<ul style="list-style-type:circle">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

Square:

<ul style="list-style-type:square">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>

None:

<ul style="list-style-type:none">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ul>


Ordered HTML Lists

An ordered list starts with the <ol> tag. Each list item starts with the <li> tag.
The list items will be marked with numbers:

Example

<ol>
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>


Ordered HTML Lists - The Type Attribute

A type attribute can be added to an ordered list, to define the type of the marker:
Type Description
type="1" The list items will be numbered with numbers (default)
type="A" The list items will be numbered with uppercase letters
type="a" The list items will be numbered with lowercase letters
type="I" The list items will be numbered with uppercase roman numbers
type="i" The list items will be numbered with lowercase roman numbers

Numbers:

<ol type="1">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Uppercase Letters:

<ol type="A">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Lowercase Letters:

<ol type="a">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Uppercase Roman Numbers:

<ol type="I">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>

Lowercase Roman Numbers:

<ol type="i">
  <li>Coffee</li>
  <li>Tea</li>
  <li>Milk</li>
</ol>


HTML Description Lists

HTML also supports description lists.
A description list is a list of terms, with a description of each term.
The <dl> tag defines the description list, the <dt> tag defines the term (name), and the <dd> tag describes each term:

Example

<dl>
  <dt>Coffee</dt>
  <dd>- black hot drink</dd>
  <dt>Milk</dt>
  <dd>- white cold drink</dd>
</dl>


Nested HTML Lists

List can be nested (lists inside lists):

Example

<ul>
  <li>Coffee</li>
  <li>Tea
    <ul>
      <li>Black tea</li>
      <li>Green tea</li>
    </ul>
  </li>
  <li>Milk</li>
</ul>

List items can contain new list, and other HTML elements, like images and links, etc.

Horizontal Lists

HTML lists can be styled in many different ways with CSS.
One popular way, is to style a list to be displayed horizontally:

Example

<!DOCTYPE html>
<html>

<head>
<style>
ul#menu li {
    display:inline;
}
</style>
</head>

<body>

<h2>Horizontal List</h2>

<ul id="menu">
  <li>HTML</li>
  <li>CSS</li>
  <li>JavaScript</li>
  <li>PHP</li>
</ul>

</body>
</html>

With a little extra style, you can make it look like a menu:

Example

ul#menu {
    padding: 0;
}

ul#menu li {
    display: inline;
}

ul#menu li a {
    background-color: black;
    color: white;
    padding: 10px 20px;
    text-decoration: none;
    border-radius: 4px 4px 0 0;
}

ul#menu li a:hover {
    background-color: orange;
}

Chapter Summary

  • Use the HTML <ul> element to define an unordered list
  • Use the HTML style attribute to define the bullet style
  • Use the HTML <ol> element to define an ordered list
  • Use the HTML type attribute to define the numbering type
  • Use the HTML <li> element to define a list item
  • Use the HTML <dl> element to define a description list
  • Use the HTML <dt> element to define the description term
  • Use the HTML <dd> element to define the description data
  • Lists can be nested inside lists
  • List items can contain other HTML elements
  • Use the CSS property display:inline to display a list horizontally


HTML List Tags

Tag Description
<ul> Defines an unordered list
<ol> Defines an ordered list
<li> Defines a list item
<dl> Defines a description list
<dt> Defines the term in a description list
<dd> Defines the description in a description list

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