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addClass
removeClass
toggleClass
hasClass
css
computedStyle
cssVar
Query - CSS
The CSS Manipulation methods in Query allow you to easily modify classes and CSS properties of elements, providing powerful tools for dynamic styling in your Semantic UI components.
addClass
Adds one or more classes to the set of matched elements.
Syntax
$('selector').addClass(className)Parameters
| Name | Type | Description |
|---|---|---|
| className | string | One or more class names to be added |
Returns
Query object (for chaining).
Usage
Standard
// Add a class to all paragraphs$('p').addClass('highlighted');Shadow DOM
// Add a class to the user name in a user-profile web component$$('user-profile').find('.user-name').addClass('premium-user');removeClass
Removes one or more classes from the set of matched elements.
Syntax
$('selector').removeClass(className)Parameters
| Name | Type | Description |
|---|---|---|
| className | string | One or more class names to be removed |
Returns
Query object (for chaining).
Usage
Standard
// Remove a class from all buttons$('button').removeClass('disabled');Shadow DOM
// Remove the 'offline' class from the status indicator in a user-profile$$('user-profile').find('.status-indicator').removeClass('offline');toggleClass
Toggles one or more classes for the set of matched elements.
Syntax
$('selector').toggleClass(className)Parameters
| Name | Type | Description |
|---|---|---|
| className | string | One or more class names to be toggled |
Returns
Query object (for chaining).
Usage
Standard
// Toggle a class on all list items$('li').toggleClass('active');Shadow DOM
// Toggle the 'expanded' class on the user bio in a user-profile$$('user-profile').find('.user-bio').toggleClass('expanded');hasClass
Determines whether any of the matched elements are assigned the given class.
Syntax
$('selector').hasClass(className)Parameters
| Name | Type | Description |
|---|---|---|
| className | string | The class name to search for |
Returns
boolean - true if the class exists on any of the matched elements, false otherwise.
Usage
Standard
// Check if any paragraph has a specific classif ($('p').hasClass('important')) { console.log('There is an important paragraph');}Shadow DOM
// Check if the user has admin privileges in a user-profileif ($$('user-profile').find('.user-role').hasClass('admin')) { console.log('This user has admin privileges');}css
Get the value of a computed style property for the first element in the set of matched elements or set one or more CSS properties for every matched element.
Syntax
// Getter$('selector').css(propertyName, null, options)
// Setter$('selector').css(propertyName, value, options)$('selector').css({property1: value1, property2: value2}, options)Parameters
| Name | Type | Description |
|---|---|---|
| propertyName | string | CSS property name |
| value | string | Value to set for the CSS property |
| options | object | Additional options for getting/setting CSS |
Options
| Name | Type | Default | Description |
|---|---|---|---|
| includeComputed | boolean | false | Include computed styles when getting CSS value |
Returns
- When getting: The value of the specified CSS property.
- When setting: Query object (for chaining).
Usage
Standard
// Get a CSS property valueconst color = $('p').css('color');
// Set a CSS property$('p').css('color', 'blue');
// Set multiple CSS properties$('p').css({ color: 'blue', fontSize: '16px'});Shadow DOM
// Get the background color of the avatar in a user-profileconst avatarBg = $$('user-profile').find('.user-avatar').css('background-color');
// Set the font size of the user name in a user-profile$$('user-profile') .find('.user-name') .css('font-size', '18px');
// Style the action buttons in a user-profile$$('user-profile').find('.action-buttons').css({ display: 'flex', justifyContent: 'space-between', marginTop: '10px'});computedStyle
Get the value of a computed style property for the first element in the set of matched elements.
CSS Performance This is an alias for
csswith{ computedStyle: true }option. In many cases you will want to get the css style as it appears in the page and not just if it has a css rule applied. This however can trigger a reflow, which means this behavior is opt-in.
Syntax
$('selector').computedStyle(propertyName)Parameters
| Name | Type | Description |
|---|---|---|
| propertyName | string | CSS property name |
Returns
The computed value of the specified CSS property.
Usage
Standard
// Get the computed font size of a paragraphconst fontSize = $('p').computedStyle('font-size');console.log(fontSize); // e.g., "16px"Shadow DOM
// Get the computed width of an element in a user-profileconst avatarWidth = $$('user-profile').find('.user-avatar').computedStyle('width');console.log(avatarWidth); // e.g., "50px"cssVar
Get or set the value of a CSS custom property (CSS variable).
Syntax
Get
$('selector').cssVar(variableName)Set
$('selector').cssVar(variableName, value)Parameters
| Name | Type | Description |
|---|---|---|
| variableName | string | The name of the CSS variable (without ’—‘) |
| value | string | (Optional) The value to set for the variable |
Returns
- When getting: The value of the specified CSS variable.
- When setting: Query object (for chaining).
Usage
Standard
// Get the value of a CSS variableconst primaryColor = $(':root').cssVar('primary-color');console.log(primaryColor); // e.g., "#007bff"
// Set the value of a CSS variable$(':root').cssVar('primary-color', '#0056b3');Shadow DOM
// Get the value of a CSS variable in a user-profileconst avatarSize = $$('user-profile').cssVar('avatar-size');console.log(avatarSize); // e.g., "50px"
// Set the value of a CSS variable in a user-profile$$('user-profile').cssVar('avatar-size', '60px');