In HTML, the rule can only have one resource source condition means that a rule or directive should only specify one resource source. The resource source refers to the element or attribute that is being targeted by the rule.
For example, let’s consider a CSS rule that targets a specific HTML element with a class name. The correct format would be:
.my-class {
color: red;
}
In this case, the resource source is the class name “my-class”, and the rule only targets elements with that specific class. It doesn’t specify multiple resource sources like class names, IDs, or element types.
Incorrect usage of multiple resource sources in a rule can lead to unexpected behavior or conflicts between different styles targeting different elements.
Let’s consider an incorrect example where multiple resource sources are used in a single rule:
.my-class, h1 {
color: red;
}
In this case, the rule is targeting both elements with the class “my-class” and all <h1> elements. This violates the rule that only one resource source should be specified in a single rule.
It is important to follow this rule in order to maintain clarity, readability, and consistency in your code.