


Summary of web page and browser compatibility issues (draft1)_javascript skills
1. The getYear method of date object
The result returned by IE getYear() is the same as the result of getFullYear(), but ECMA262 clearly stipulates that getYear returns "year- 1970". Some websites use getYear to return the year, which results in logical differences between relatively standardized browsers such as IE and FF.
2.DOM
1. Event model
2.document.elementFromPoint
This method of document is an IE extension and can return the element based on the client area coordinates of the viewport. DOM node. Safari also supports this method, but the coordinates represent the coordinates after the web page content is laid out (the coordinates are the coordinates of the client area of the browser window). The difference between the two means that if you want to get the element node through the position of the mouse pointer, IE can directly return the element to the client area coordinates (clientX, clientY) of the event, but Safari needs to use scrollX and scrollY to return it. Both are reasonable in the sense of this interface. The meaning of this coordinate is not clearly defined in MSDN, but IE is simpler in terms of interface usage, while Safari requires coordinate conversion.
3.CSS
4.layout
5. Plug-in and ActiveX
As we all know, IE is compatible with third-party programs. It is ActiveX technology; while Firefox, Safari, Chrome, and Opera use NPAPI plug-in technology. In terms of interface level, the plug-in interface level of the two is lower (both are C function pointers). They use abstract interfaces and data types to encapsulate the interaction logic between the browser and third-party programs, but the browser and plug-in programs are tightly coupled; ActiveX shields the process and thread models and is a loosely coupled interaction method. This is why legal ActiveX will not crash IE in IE, but plug-ins with the same function may crash the browser. The difference in this feature is also one of the bigger differences in browser compatibility.
6. Others
1. The forum sets cookies based on the browser sub-version in UserAgent. This is not reasonable because UserAgent will change with the browser version, causing the original cookie to be effective. .

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.


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