The Power Behind the Web Pages: An Exploration of Rendering Engine
Have you ever experienced or witnessed a sports game where fans sing along with a massive visual display, like in a public arena? The image below serves as an illustration of what I mean.
I see. The question is used as an introduction to your comparison between the workings of a browser's rendering engine and the synchronized actions of fans in a sports stadium to display a unified message.
Overview of the rendering engine
A rendering engine is a component of the web browser that is responsible for rendering and displaying web pages on the screen. It takes the HTML, CSS and JavaScript code as input and converts it into visual content that can be displayed on the user's screen. Different browsers have different rendering engines, each with its own unique features and capabilities.
Some of the most widely used rendering engines in popular browsers include:
Each of these rendering engines has its own advantages and disadvantages, and the choice of which to use is often determined by the specific needs of the browser developers. For example, WebKit is optimized for speed and performance, while Gecko prioritizes standards compliance and customization.
The critical rendering path flow?
1. Parsing
Parsing is the first step in the process of a rendering engine. During parsing, the engine takes the HTML and CSS code and converts it into a more structured and organized representation, known as the Document Object Model (DOM) and the CSS Object Model (CSSOM) trees, respectively.
In the case of HTML, the parsing process involves breaking down the code into individual elements, such as headings, paragraphs, and links, and creating a tree-like structure to represent the relationships between these elements. This structure is known as the DOM tree.
In the case of CSS, the parsing process involves converting the styles into a more organized representation, known as the CSSOM tree. This allows the engine to easily apply the styles to the elements in the DOM tree and calculate the layout of the page.
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2. Layout
The layout process, also known as reflow, is the second step in the process of a rendering engine. During this step, the engine uses the information in the DOM and CSSOM trees to calculate the size and position of each element on the page.
The layout process involves several calculations, including determining the dimensions of each element, calculating the flow of text and other content, and determining the placement of elements relative to each other. Once these calculations are complete, the engine has a clear understanding of the layout of the page and can move on to the next step, painting.
3. Painting?
The painting process starts by creating a visual representation of the background of the page, followed by the individual elements such as text, images, and shapes. Each element is painted using the information in the CSSOM tree, including the background color, border, and other styles.
Once the painting process is complete, the engine has a full visual representation of each element on the page. This information is then used in the final step, compositing, to generate the final image that is displayed on the screen.
4. Composition
In the compositing step, the engine takes into account the stacking order of the elements, as well as the transparency and blending effects applied to each element. The engine then combines the elements into a single image, ensuring that the visual representation of the page is correct, with elements appearing in the correct order and with the correct blending effects.
What's next ?
Next, we will delve into the most significant component that plays a crucial role in Javascript, the Javascript engine.
So, join me ?? on this journey as we delve into the exciting world of advanced JavaScript concepts and stay informed about the next post series outlined in the roadmap above.