1. What are W3C standards?

WEB standards are not a single standard, but a collection of standards. The web page is mainly composed of three parts: Structure, Presentation and Behavior. The corresponding standards are divided into three aspects: the structural standard language mainly includes XHTML and XML, the presentation standard language mainly includes CSS, and the behavior standard mainly includes object model (such as W3C DOM) and ECMAScript.

2. Bootstrap response principle

@media (min-width: @screen-sm-min) {// width: @screen-sm-min) {// width: @screen-sm-min } @media (min-width: @screen-md-min) {// Width: @screen-md-min; }// Large screen (large desktop display, greater than or equal to 1200…

3. Differences between HTML/XHTM

XHTML is not much different from the HTML 4.01 standard. XHTML elements must be properly nested. XHTML elements must be closed. The label name must be lowercase. XHTML documents must have a root element.

4. Page structure and layout

Layout can be either coding or visual. Coding involves semantic tag (also including DIV + CSS) layout, IFrame framework (special place use) layout and table layout (only for some special places, not recommended for the whole site use), specific you can baidu to understand the relevant knowledge.

If it is visual interaction, it will be more. Every year, there will be new design layouts, such as the advanced parallax layout, full-screen layout, waterfall flow, seamless puzzle layout, etc., which are not limited to the traditional layout; Traditional e-commerce, information mostly use single column, two column or three column layout, and more column layout; Resolution related widescreen layout and narrow screen layout, inductive layout. There are so many choices and so many things to learn. There are many more layouts to explore and experience. I told you what I know. As for the mobile end, some examples: vertical list, horizontal row squares, nine squares, TAB switch type, accordion layout (multiple categories and their contents are displayed at the same time), drawer/sidebar, TAB scene type), because the screen is small, to increase user experience can be based on the specific situation of different layout.

5. BootStrap learning notes and summary of advantages and disadvantages

Advantages:

  • One of BT’s strengths is its ability to adjust pages to fit the user’s screen size so that they behave well across all sizes.

  • BT pre-defines a lot of CSS classes, when using directly to give the corresponding class name can be, such as text-left, text-align,.table, etc.. The most representative is the BTN class, BT defines a. BT base class, if you want other styles can be extended on this base class, to achieve different visual effects.

  • BT JavaScript plugins are very rich, both can be used ready-made and can be expanded, BT provides an integrated board of BT. Js you can directly take over the use or single use of *.js can be introduced.

Inadequate:

  • There is also a big problem with IE compatibility. BT sets all the element box models as border-box, which is the box model in IE promiscuous mode. This leads to incompatibility with IE. In addition to the use of a large number of H5 tags and CSS3 syntax, these grammar tag compatibility also has a large problem, of course, there are many compatible Internet Explorer methods, but the need to introduce other files, some are not small, is bound to lead to slow loading, affect the user experience.

  • Bittorrent is definitely not compatible with IE6 and ie7, and support for IE8 also requires some extra files. Media query of IE8 needs response.js to realize

  • BT does not support the old compatibility mode of IE. To get Internet Explorer running in the latest rendering mode, it is recommended to add this
    tag to your page:

BT belongs to the front-end UI library, which can quickly build front-end pages and design responsive interfaces. It can also redesign components using saas.

6, JQeury learning notes, advantages and disadvantages summary

Advantages:

  • JQuery decouples scripts from pages and is the js library of choice for DOM manipulation.

  • Doing the most with the least code is the watchword of jQuery, and it lives up to its name. With its advanced selector, developers can achieve amazing results with just a few lines of code. Developers don’t have to worry too much about browser differences. In addition to full Ajax support, it has a number of other abstractions that make programming more efficient for developers. JQuery takes JavaScript to a higher level. Here is a very simple example: the code looks like this: $(” p.eat “).addclass (“ohmy”).show(“slow”); With this short code, developers can iterate through all the

    elements in the “Neat” class, then add the “Ohmy” class to it, while slowly animating each paragraph. This can be done in a single line of code without checking the client browser type, writing loops, or writing complex animation functions.

  • Performance Of the large JavaScript frameworks, jQuery has the best understanding of performance. Despite all the new features in different versions, the slimmest version is only 18KB in size, a number that will be hard to reduce. There are significant performance improvements with each release of jQuery.

  • There are about thousands of plug-ins based on jQuery. Developers can use plug-ins for form validation, chart categories, field hints, animations, progress bars, and more.

  • Of course, it takes a little time to really learn jQuery, especially if you have to write a lot of code or your own plug-in. However, developers can take a divide-and-conquer approach, and jQuery provides so much sample code that it’s easy to get started.

Inadequate:

  • Backward incompatible

  • Plug-in compatibility.

  • JQuery stability

  • In large frameworks, the jQuery core code base has relatively poor support for animation and special effects.

7. What exactly does “high cohesion, low coupling” mean?

‘High cohesion, low coupling’ is how closely each module is related to each other in a project, relative to the code. The closer the modules are related to each other, the higher the coupling and the less independent the modules are! And vice versa; The degree to which each element in a module is closely related, the higher the degree of connection between each element (statement, program segment), the higher the cohesion, i.e., ‘high cohesion’! For example, if you have 20 good method calls in a project, but change one of them and change the other 19, that’s high coupling! Poor independence! Nowadays, the design of software structure requires “high cohesion, low coupling” to ensure the high quality of software! Mark!!!

8. Have a certain understanding of the technical principles of front-end and back-end joint development (Ajax and Json), understand DOM and Xml concepts, and be familiar with the way of front-end and back-end interaction.

  • Principle of Ajax asynchronous interaction: Ajax is composed of JavaScript, XMLHTTPRequest and DOM object at its core. It sends asynchronous requests to the server through XMLHTTPRequest object, obtains data from the server, and then uses JavaScript to operate DOM and update the page.

  • Json: I usually use AJAX asynchronously to fetch Json data.

  • DOM: Document object model, where everything in a web page is a DOM node, the root node is < HTML >, and it can be nested wirelessly. Used to get or set the attributes of the label in the document, for example, get or set the value of the input form.

  • BOM: Browser object model. Gets or sets the properties and behavior of the browser, such as creating a new window, getting the screen resolution, and browser version.

  • XML: Designed to transfer and store data, designed to format and display data. Just plain text. – Front and background interaction modes:

9. Differences between GET and POST requests

  • The data submitted by GET is placed after the URL, ending with? Split URL and transfer data with & between parameters such as editposts.aspx? Name =test1&id=123456. The POST method places the submitted data in the Body of the HTTP package.

  • The data submitted by GET is limited in size (because browsers have limits on the length of urls), while the data submitted by the POST method is not limited.

  • GET uses Request.QueryString to GET the value of a variable, while POST uses Request.Form to GET the value of a variable.

  • When submitting data through GET, the user name and password will appear in the URL. If the page can be cached or someone else can access the machine, the user’s account and password can be obtained from the history.

Original publication time: May 31, 2018

Author: O_ Wo Huo _O

If you need to reprint, please contact the original author