JavaScript Learning Notes (10)----Client detection and DOM

Client-side detection:

(i) Capacity testing

Capability detection is the ability to identify browsers.

The ability to detect a particular browser before writing code. For example, a script might want to detect the existence of a function before calling it.

(ii) Quirks detection

Quirks are actually bugs in the browser implementation. Quirks detection usually involves running a small piece of code and then determining whether a browser has a quirk.

(iii) User agent detection

The browser is identified by detecting the user-agent string.

Dom

(i) Node hierarchy

In an HTML page, the document element is used as a

Each piece of markup can be represented by a node in the tree: The HTML element is represented by an element node, the attribute is represented by an attribute node, the document type is represented by a document type node, and the comment is represented by an annotation node.

There are 12 node types, all of which inherit from a base type.

1.Node type

All node types in JavaScript inherit from the node type, so all node types share the same basic properties and methods.

Each node has a NodeType property that indicates the type of the node.

12 numeric Changlianglai indicates the node type:

1 = = Node.element_node

2 = = Node.attribute_node

3 = = Node.text_node

4 = = Node.cdata_section_node

5 = = Node.entity_reference_node

6 = = Node.entity_node

7 = = Node.processing_instruction_node

8 = = Node.comment_node

9 = = Node.document_node

Ten = = Node.document_type_node

= = Node.document_fragment_node

* = Notation_node

JavaScript Learning Notes (10)----Client detection and DOM