What are the js native selectors?

js native selectors include getElementById(), getElementsByClassName(), getElementsByTagName(), querySelector(), querySelectorAll(), etc. Detailed introduction: 1. getElementById() selects elements through their unique identifiers, and it returns elements with specified IDs as results, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

JavaScript provides some native selectors for selecting and manipulating HTML elements. These native selectors can be used through JavaScript APIs and methods. The following are common native selectors in JavaScript:

1. getElementById():

The getElementById() method selects elements by their unique identifier (ID). It returns the element with the specified ID as result.

   var element = document.getElementById("myElement");

In the above example, the getElementById() method selects the element with the ID "myElement" and assigns it to the variable element.

2. getElementsByClassName():

The getElementsByClassName() method selects elements by their class names. It returns a collection of all elements with the specified class name.

   var elements = document.getElementsByClassName("myClass");

In the above example, the getElementsByClassName() method selects all elements with the class name "myClass" and returns them as a collection to the variable elements.

3. getElementsByTagName():

The getElementsByTagName() method selects elements by their tag names. It returns a collection of all elements with the specified tag name.

   var elements = document.getElementsByTagName("p");

In the above example, the getElementsByTagName() method selects all p elements and returns them as a collection to the variable elements.

4. querySelector():

The querySelector() method selects elements through CSS selectors. It returns the first element matching the selector.

   var element = document.querySelector(".myClass");

In the above example, the querySelector() method selects the first element with the class name "myClass" and assigns it to the variable element.

5. querySelectorAll():

The querySelectorAll() method selects elements through CSS selectors. It returns a collection of all elements matching the selector.

   var elements = document.querySelectorAll("p");

In the above example, the querySelectorAll() method selects all p elements and returns them as a set to the variable elements.

These native selectors are commonly used selectors in JavaScript and are used to select and operate HTML elements. They provide flexible selection and query functions, allowing you to select a single element or multiple elements as needed, and perform corresponding operations and processing.

It should be noted that the return result of a native selector is usually a collection (such as NodeList), which needs to be traversed and operated according to specific requirements. In addition, the performance of native selectors may be affected by the complexity of the page structure and the complexity of the selector, so when using native selectors, attention should be paid to the simplicity and performance optimization of the selector.

In summary, JavaScript provides some native selectors, including getElementById(), getElementsByClassName(), getElementsByTagName(), querySelector() and querySelectorAll(). Proper use of these native selectors can select and operate HTML elements. If you have any further questions please feel free to let me know.

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