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JavaScript traversal of HTML form elements and form definitions, javascript form
The following JavaScript code traverses all HTML elements (html dom elements) through the document object ).
<Html> <meta http-equiv = "Content-Type" content = "text/html; charset = UTF-8 ">
Note: Code explanation
(1). hasAttribute ("id") to determine whether the "id" attribute exists. If a specified attribute exists, the hasAttribute () method returns true; otherwise, false;
(2). id, return the element id;
(3). getAttribute ("fieldtype") returns the specified attribute value of the element node.
Using the above Code, we will consider the following:
- When defining a form, key information of the form data item, such as the data type, is directly defined through the attribute of the element;
- By traversing the form, get the form design definition and its business data value, and directly convert the two to BSON type storage high MongoDB;
- When presenting or editing a form, define the form design as a template and write it back to set the data content.
The following content is provided for reference to W3School.
Html dom Document Object Document Object
Each HTML Document loaded into the browser will become a Document Object.
The Document object allows us to access all elements in the HTML page from the script.
Tip: The Document object is part of the Window object and can be accessed through the Document DOC ument attribute.
Html dom getElementsByTagName () method
- Definition and usage
The getElementsByTagName () method returns a set of objects with the specified tag name.
- Syntax
document.getElementsByTagName(tagname)
- Description
The getElementsByTagName () method returns the order of elements in the document.
If you pass the special string "*" to the getElementsByTagName () method, it returns a list of all elements in the document. The order of elements is the order in the document.
Html dom Element Object html dom Node In html dom (Document Object Model), each part is a node:
- The document itself is a document Node
- All HTML elements are element nodes.
- All HTML attributes are attribute nodes.
- The text in the HTML element is a text node.
- Annotation is a comment node.
Element Object
- In the html dom, an Element object represents an HTML Element.
- Element objects can have child nodes of the Element node, text node, and comment node types.
- The NodeList object indicates the node list, such as the child node set of the HTML element.
- The element can also have attributes. Attribute is an attribute node
Html dom nodeType attributes Return values of nodeName and nodeValue attributes for each node type:
Serial number
Node Type
NodeName returned
Return nodeValue
1
Element
Element name
Null
2
Attr
Attribute name
Attribute Value
3
Text
Text
Node content
4
CDATASection
Cdata-section
Node content
5
EntityReference
Object Reference name
Null
6
Entity
Entity name
Null
7
ProcessingInstruction
Target
Node content
8
Comment
Comment
Comment text
9
Document
Document
Null
10
DocumentType
Document Type name
Null
11
DocumentFragment
Document Fragment
Null
12
Notation
Symbol name
Null
Refer:
W3School offers: http://www.w3school.com.cn/jsref/dom_obj_document.asp
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