The difference between a class and an ID selector in a CSS selector

Differences between class and ID selectors

Learning the class selector and ID selector, we will find that there are a lot of similarities between them, is not the two can be common? Let's not be anxious to summarize their similarities and differences in the first few years:

same point: can be applied to any element
Different points:

1.The ID selector can only be used once in a document . Unlike class selectors, an ID selector can only be used once, and only once, in an HTML document. The class selector can be used more than once.

The following code is correct:

class= "Stress" class= "Stress"> Courage </span> to answer the questions asked by the teacher. </p>

And the following code is wrong:

id= "Stress" id= "Stress"> Courage </span> to answer the questions asked by the teacher. </p>

2 . You can use the class selector word list method to set multiple styles for an element at the same time. we can set multiple styles for one element at the same time, but only with the method of the class selector, the ID selector is not possible (the list of ID words cannot be used).

The following code is correct (see the Code Editor on the right for the full code)

class= "Stress bigsize"> Third grade </span> next semester, our class has a public class ...</p>

The function of the above code is to set the text color to red for the "third grade" three text and the font size to 25px.

The following code is incorrect (see the Code Editor on the right for the full code)

id= "Stressid Bigsizeid"> Third grade </span> next semester, our class has a public class ...</p>

The above code can not be implemented for the "third grade" three text set the text color is red and the font size for the effect of 25px.

The difference between a class and an ID selector in a CSS selector