Manipulating CSS with jQuery Quiz Quiz

Explore core techniques for manipulating CSS properties using jQuery selectors, methods, and chaining. Assess your understanding of dynamic style changes and best practices for adding, removing, and modifying CSS classes and styles programmatically.

1. Setting a Single CSS Property

   Which jQuery method allows you to change the background color of an element with the class 'header' to blue?

   1. $('.header').setCSS('background-color', 'blue');
   2. $('.header').changeStyle('background-color', 'blue');
   3. $('.header').style('background-color', 'blue');
   4. $('.header').css('background-color', 'blue');

   Explanation: The correct method to modify a single CSS property in jQuery is the .css() method. Options like .setCSS(), .style(), and .changeStyle() do not exist in standard jQuery and will result in errors. Only the .css() syntax correctly applies the background color to targeted elements.

2. Adding and Removing CSS Classes

   If you want to add the class 'active' and remove the class 'inactive' from all elements with the class 'menu-item', which is the most efficient jQuery code?

   1. $('.menu-item').addCSS('active').removeStyle('inactive');
   2. $('.menu-item').insertClass('active').deleteClass('inactive');
   3. $('.menu-item').classAdd('active').classRemove('inactive');
   4. $('.menu-item').addClass('active').removeClass('inactive');

   Explanation: Chaining .addClass('active') and .removeClass('inactive') provides a concise and effective way to update classes with jQuery. Methods like .insertClass(), .deleteClass(), .addCSS(), .removeStyle(), .classAdd(), and .classRemove() are not valid jQuery functions and will not work as intended.

3. Retrieving a Computed CSS Value

   How can you obtain the current font size of the first element with the id 'content' using jQuery?

   1. $('#content').getStyle('font-size');
   2. $('#content').getCSS('font-size');
   3. $('#content').css('font-size');
   4. $('#content').style('font-size');

   Explanation: Using .css('font-size') on a jQuery object returns the computed value of that CSS property for the first matched element. The methods getStyle(), getCSS(), and style() do not exist in standard jQuery, so they would not retrieve the value as expected.

4. Setting Multiple CSS Properties at Once

   What is the correct way to set both the color to red and text-align to center for elements with class 'notice' using jQuery?

   1. $('.notice').css('color', 'red', 'text-align', 'center');
   2. $('.notice').css({'color': 'red', 'text-align': 'center'});
   3. $('.notice').addCSS({'color': 'red', 'text-align': 'center'});
   4. $('.notice').style({'color': 'red', 'text-align': 'center'});

   Explanation: Passing an object to .css() allows you to set multiple CSS properties in a single call. The second option mistakenly attempts to use multiple string arguments, which is not supported. The third and fourth answers use incorrect methods, as .addCSS() and .style() are not valid in jQuery.

5. Toggling a CSS Class

   Which jQuery method can you use to switch the class 'highlight' on and off when a button is clicked?

   1. $('.highlight').classToggle('highlight');
   2. $('.highlight').toggleClass('highlight');
   3. $('.highlight').changeClass('highlight');
   4. $('.highlight').switchClass('highlight');

   Explanation: The .toggleClass('highlight') method adds the class if it’s not present and removes it if it is, making it perfect for toggling. Other options like .changeClass(), .classToggle(), and .switchClass() are either not available in standard jQuery or serve a different purpose, and thus won’t work for simple toggling.