- :first-child and :last-child 4:15
- :first-child and :last-child Challenge 2 objectives
- :only-child and :empty 4:58
- Substring Matching Attribute Selectors - "Begins With" and "Ends With" 8:19
- Substring Matching Attribute Selectors - "Contains" 6:44
- Substring Matching Attribute Selectors Challenge 3 objectives
- Element States Pseudo-Classes 6:20
- Structural and Element States Pseudo-Classes Review 5 questions
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Element States Pseudo-Classes
6:20Like user-action pseudo-classes, CSS has UI element states pseudo-classes that let us target elements based on user interaction states.
So once again, we'll need to launch a new
work space for this lesson.
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And once we click the preview button for
our work space,
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we can see how it brings up the contact
form we used in the previous stage,
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with the addition of a few check boxes.
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So back in the CSS basics course, we
covered user action pseudo-classes that
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target elements based on the user's
interaction with an element.
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So let's do a quick review of one of those
selectors.
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So I'm gonna open up the style.css file
inside the CSS directory.
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So for example to style a text field and
text area once they have received focus,
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we can add the focus pseudo class to a
selector.
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So let's target input elements and add
the
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focus pseudo class and we're going to
group this with the textarea,
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element selector and we're also gonna give
it the focus pseudo class.
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And on focus we're gonna change those
element's border color to an aqua green.
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So let's set it to a hex value of pounds
five two b a b three.
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So, once we save our stylesheet and
refresh the page,
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notice how once we click inside a field,
the border color turns aqua green.
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[BLANK_AUDIO]
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So, very similar to these user action
pseudoclasses.
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CSS also has UI element states pseudo
classes that let
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us target elements based on a few other
user interaction states and
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their most commonly used first styling
form elements.
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So let's take a look at two of the most
common ones.
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So one of the UI element state selectors
is the disabled selector.
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Which selects UI elements like buttons or
input fields that are in disabled state.
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So, all form fields and buttons by default are usually enabled.
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But when an element is disabled, we cannot
select it or click on it.
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And if it's a text field, it cannot accept
any input.
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So, to target any disabled form element.
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We'll need to write the disabled
pseudo-class by typing colon,
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followed by disabled.
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And then let's change a disabled element's
background, to light grey.
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So, we're gonna define a hex value, pound
ddd, which as we can see,
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gives us a light shade of grey.
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So now this will target all UI elements
that are in a disabled state.
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Which currently, if we take a look at our
index.html file, none of them are.
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So, we'll need to add a disabled boolean
attribute to one of our text fields.
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So let's add it to our email field.
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So right here on line 19,
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right after the placeholder attribute,
let's go ahead and type disabled.
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So once we do that, let's save our HTML
file, and let's go back and
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save our style sheet.
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And we'll bring up the preview, and hit
refresh.
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So now we're able to see that the field
with the disabled attribute, so
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the Email field, is the only element with
the light gray background.
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And notice how I'm not able to click
inside and
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add any text, because it's disabled.
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Now if we need to be more specific we can
tell the browser that we only one to
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target disabled input elements.
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And we'll do that by simply adding the
input type selector,
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right before the pseudo class.
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Next, with the checked pseudo class,
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we can install form elements that are in a
checked state.
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Like a check box or radio button.
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So let's use the checked state of our three
check boxes down here, and
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we're going to create a selector that
highlights the sibling label elements
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with a bold font weight once a check box
is checked.
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And since we're gonna want to target the
label that's adjacent to a check box.
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We're going to use a familiar selector to
target them.
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So first, let's use an attribute selector
to select input elements
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whose type attribute is checkbox.
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Then after the square brackets we're going
to add the checked pseudo class.
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Then we'll use the plus sign or the
adjacent sibling combinator to select
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the label that is an immediate sibling of
the check box.
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So if we go back and take a look at the
HTML for our labels and
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checkboxes, notice how each set of labels
and checkboxes are sibling elements.
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So let's add a font-weight property.
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And set the value to bold.
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All right.
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So once we save our style sheet, and bring
up the preview and hit Refresh.
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Once a check box is checked or
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in a checked state, that adjacent label
takes on the bold font weight style.
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Before we move on, let's do a quick review
of some of what we've learned so
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far about structural pseudo-classes,
substring matching attribute selectors,
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and element state pseudo-classes.
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First, the first child and last child
pseudo classes,
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let us select elements that are the first
or last child of a parent element.
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We're also able to target elements with no
siblings,
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with the only child pseudo class.
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And we can target empty elements, with no
children or
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content with the empty pseudo class.
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And with substring matching attribute
selectors we can match specific pieces of
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an attribute's value.
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Like certain letters or words.
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The caret character tells the browser to
match a piece of code,
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that's at the beginning of an attribute's
value.
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While the dollar sign matches a piece at
the end of an attribute's value.
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And with the asterisk, we can match any
part of an attribute's value.
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So many of these selectors,
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can come to our rescue when we don't have
control over the HTML.
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Finally, when styling forms, we can target
certain element states,
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like the checked state of a radio button
and check box or a disabled text field.
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Up next we'll take a close look at more
advanced selectors,
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we can use to make our style sheets
cleaner and more powerful.
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