


A drop-down menu combining css and js supports mainstream browsers_javascript skills
First statement:
Although I have worked in a web front-end position for many years, the technical requirements of the position are not high. HTML and CSS are mostly used, but JavaScript is rarely original and is basically copied and modified. Therefore, when I actually write it, I find that the foundation is not solid. I learn and practice at the same time, and I gain a lot.
Rendering:
No more nonsense, let’s post the code
1. css code
a:link{color:white;text-decoration:none;}
a:visited{color:white;text-decorative:none;}
a:hover{color:white;text-decorative:none;}
a:active{color:white;text-decorative:none;}
li{float:left;display:inline;background-color:#003366;width:120px;text-align:center;margin:2px;padding:10px 0 5px 0;position:relative;}
.limouseover{background-color:#0033ff;color:red;}
.limouseout{background-color:#003366;color:black;}
li ul{display:none;width:120px;position:absolute;left:0;top:30px;}
li ul li{margin:0px auto;border-top:1px solid #006699;}
2. JavaScript code
3. html code
<script>var menu1=new menu("menu1");</script>
Description:
1. Considering that ul and li pages are commonly used, you can add #menu1 before css to limit the scope of the menu style.
2. The js mainly listens for the mouse move in and removal events, and switches to the limouseover and limouseout styles accordingly; at the same time, it changes the display attribute of the submenu to achieve the display and hide function.
3. The same page can be called repeatedly without conflict. The JavaScript code in the html code is the calling instance. The previous menu1 is an arbitrary variable name, and the menu1 in the brackets is the id in the html page.
Disadvantages of this example:
1. The styles of mouseover and mouseout of menu li and submenu li are the same, that is, the same color and font, and no separate settings are implemented.
2. Since it needs to be compatible with Ie6 and ie7, while position:absolute is used, the left and top attributes are added. The top should be set according to the overall height of the menu li.

JavaScript core data types are consistent in browsers and Node.js, but are handled differently from the extra types. 1) The global object is window in the browser and global in Node.js. 2) Node.js' unique Buffer object, used to process binary data. 3) There are also differences in performance and time processing, and the code needs to be adjusted according to the environment.

JavaScriptusestwotypesofcomments:single-line(//)andmulti-line(//).1)Use//forquicknotesorsingle-lineexplanations.2)Use//forlongerexplanationsorcommentingoutblocksofcode.Commentsshouldexplainthe'why',notthe'what',andbeplacedabovetherelevantcodeforclari

The main difference between Python and JavaScript is the type system and application scenarios. 1. Python uses dynamic types, suitable for scientific computing and data analysis. 2. JavaScript adopts weak types and is widely used in front-end and full-stack development. The two have their own advantages in asynchronous programming and performance optimization, and should be decided according to project requirements when choosing.

Whether to choose Python or JavaScript depends on the project type: 1) Choose Python for data science and automation tasks; 2) Choose JavaScript for front-end and full-stack development. Python is favored for its powerful library in data processing and automation, while JavaScript is indispensable for its advantages in web interaction and full-stack development.

Python and JavaScript each have their own advantages, and the choice depends on project needs and personal preferences. 1. Python is easy to learn, with concise syntax, suitable for data science and back-end development, but has a slow execution speed. 2. JavaScript is everywhere in front-end development and has strong asynchronous programming capabilities. Node.js makes it suitable for full-stack development, but the syntax may be complex and error-prone.

JavaScriptisnotbuiltonCorC ;it'saninterpretedlanguagethatrunsonenginesoftenwritteninC .1)JavaScriptwasdesignedasalightweight,interpretedlanguageforwebbrowsers.2)EnginesevolvedfromsimpleinterpreterstoJITcompilers,typicallyinC ,improvingperformance.

JavaScript can be used for front-end and back-end development. The front-end enhances the user experience through DOM operations, and the back-end handles server tasks through Node.js. 1. Front-end example: Change the content of the web page text. 2. Backend example: Create a Node.js server.

Choosing Python or JavaScript should be based on career development, learning curve and ecosystem: 1) Career development: Python is suitable for data science and back-end development, while JavaScript is suitable for front-end and full-stack development. 2) Learning curve: Python syntax is concise and suitable for beginners; JavaScript syntax is flexible. 3) Ecosystem: Python has rich scientific computing libraries, and JavaScript has a powerful front-end framework.


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