① text-align:center ② margin:0 auto ③ top, left 50%; Margin: – (half div height) auto) ④ display:table-cell ⑤ line-height ⑥ flex ⑦ vertical-align: middle ⑧

1. Given the width and height of block-level elements, use absolute positioning and margins to achieve horizontal and vertical center (parent element position:relative, child element)

position:absolute; top:50%; left:50%; margin-top:-height/2; Margin – left: – width / 2)

2. Use CSS3 display:flex (IE compatibility issues) (parent element style attribute display:flex; 3. Absolute Positioning +CSS3 Transform

• the position in the middle

margin:0,auto; The center element, but sometimes we have to make the element position:absolute; Margin :0,auto; margin:0,auto; The center is invalid.

Data types (null, undefind, number, Object, String, Boolean), basic data types and the difference between the reference data type

The main difference between primitive data types and reference types is that primitive data types are allocated on the stack, while reference types are allocated on the heap (requiring the Java concept of stack, heap). The memory models of primitive and reference types are essentially different

• New ES6 features const and let; Template strings, arrow functions, object and array deconstruction, for… Of and the for… In • the difference between the arrow function and the normal function

The function keyword is not required to create a function

This keyword inherits the current context. Call ()/.apply()/.bind() cannot change the direction of this in the arrow function

.call()/.apply()/.bind()

• The Vue life cycle Created by the parent and child of the Vue is Mounted Updated Destroyed by the Vue data

Props, $emit, ref, $parent and $children, eventBus, Vuex

• Push () pop() shift() unshift() splice() sort() reverse()”

1. Js native event registration function (attachEvent, addEventListener) ps: should know about the DOM manipulation native js 2. Regular expression 3. Basic statement operation of database add, delete, change and search 4. New features of CSS3 Text -shadow, text-overflow, text-wrap, word-break, word-wrap, white-space, border-raduis, border-image 5 Understanding HTML5

1. Improve usability and user-friendly experience;

2. There are several new tags that will help developers define important content; 3. Bring more multimedia elements (video and audio) to the site; 4, can be a good replacement for Flash and Silverlight; 5. Be SEO-friendly when it comes to scraping and indexing websites; 6. Will be widely used in mobile apps and games. 6. Type of box model (IE and non-IE) 7. Understanding of float properties 8. Closures: Closures are functions that read variables inside other functions. 9. Prototype chains: Prototype chains are the properties and methods of an object, either defined in itself or defined in its own prototype object. Since the archetype is itself an object, and has its own archetype, it is formed. 10. Prototype inheritance https://blog.csdn.net/qq_4292…

② Construct inheritance: Execute the parent construct, point This to itself, and pull the parent private property ③ Combinatorial inheritance: Construct inheritance and prototype inheritance combination. Note the comment area, do not use this method to override or add a method when inheriting, otherwise the entire prototype will be modified, resulting in collapse of the clone prototype chain inheritance: the waiting for the inherited prototype object is cloned, and then assigned to the inherited prototype object. ⑤ Parasitic combinatorial inheritance: the parent prototype object is directly assigned to an empty property constructor, and then the empty property constructor instance is assigned to a subclass prototype object. The basic purpose of this method is to solve the occurrence of two constructs inherited by the parent instance

11. Event bubbling: When an element receives an event, it passes the event to its parent, up to window 12. How to work with various browsers (conditional comments, hacks, etc.)

[1]IE9-(<! --[if IE]><! [endif]-->) [2] only single IE(<! --[if IE 6]><! [endif]-->)
  1. VPM layering, view features
  2. Single data stream
  3. HTTPS encryption mechanism is a security-oriented HTTP channel, simply speaking, is the secure version of HTTP. That is, the SSL layer is added under HTTP. HTTPS security is based on SSL, so the encryption details require SSL. It is a URI Scheme (Abstract Identifier System) that syntactically resembles the HTTP: system. For secure HTTP data transfer. HTTPS: The URL indicates that it uses HTTPS, but HTTPS has a different default port than HTTP and an encryption/authentication layer (between HTTP and TCP). Originally developed by Netscape to provide authentication and encrypted communications, this system is now widely used for security-sensitive communications over the World Wide Web, such as SSL for transactions and payments, developed by Netscape. To ensure the security of data transmission on the Internet. There are currently three versions of SSL, SSL1.0, SSL2.0, and SSL3.0. It has been widely used for authentication and encrypted data transmission between Web browsers and servers. SSL uses data encryption, authentication and message integrity verification mechanisms to provide security guarantees for the transmission of data over the network. SSL supports a variety of application layer protocols. Because SSL sits between the application layer and the transport layer, it can provide security for any application layer protocol based on a reliable connection such as TCP.
  4. TCp, utp
  5. Array insert time difference
  6. The child hooks
  7. What does it take to create a project
  8. Why Echart