Semalt: Element Attributes. Everything You Need To Know
Document Object Model (DOM) is an Application Programming Interface (API) for well-structured XML and HTML documents. API defines the ultimate structure of documents, how to access them, and how web scrapers accesses and scrapes documents across the web.
DOM works to retrieve and modify attributes present in HTML elements. With Dom, you can access element attributes and styles used in a particular document. With few scraping techniques, you can retrieve the background image of the target document.
HTML DOM Nodes
When it comes to HTML DOM, everything can be considered as a node. For instance:
- All the HTML attributes are attribute nodes;
- Comments are comment nodes;
- All HTML elements are elements nodes;
- The document itself is termed as a document node;
Document Object Model is used to access and manipulate elements within XML and HTML documents. Elements are organized and managed into a data structure (tree-like) that can easily be traversed for navigation and modification. You can add classes to DIV, body, or HTML element using Cascading Style Sheets (CSS), or interact with the elements using JS.
What you need to know about attributes property
Nodes can be accessed and manipulated using their respective index numbers, where the minimum index is "0". The attributes property works by returning a detailed collection of particular node's attributes, like the NamedNodeMap object. Note that numerical indexing will help you go through an element attribute.
The element attribute property returns a valid collection of all the attribute nodes that are registered to a particular node. In simple words, it is a NamedNodeMap. Hence it lacks Array methods. The Attribute (a pair of strings representing any data regarding the given attribute) nodes may differ depending on the browser used.
In this post, NamedNodeMap Object stands for the unstructured collection of a specific element attribute nodes. You don't have to panic in respective of the browser you've been using. NamedNodeMap object and the Attribute object is supported in major web browsers.
NamedNodeMap object comprises of a length property that you can use to determine the accurate number of attributes. After identifying the total number of attributes in a document, loop through the attributes nodes and extract your target information. When retrieving data from a text, keep into account that HTML attributes are also termed as attribute nodes comprising of properties for your Attribute object.
For Internet Explorer enthusiasts, you need to note that the attributes property tends to return a detailed collection of the possible attributes for a specific element. Once a DOM Node is generated for any given HTML element, many of the attributes relate to attributes bearing the same names. When developing an HTML source code, you can define the attributes on your HTML elements. Once your browser parses your script, a corresponding DOM with a similar node will be created. The corresponding node is termed as an object.