. Net Face Questions Summary (v)

1. Describe the difference between "=, = =, = = =" in JavaScript?

= assigned value

= = comparison is generally equal to "3" ==3//will do the type of implicit conversion, true

= = = Comparison is strictly equal to "3" ===3//First comparison type, then value comparison, false

2, see the following code output why? explain why
var a = null;
Alert (typeof a);
var b;
Alert (typeof B);
alert (c);

A is null and an object, so typeof (a) is object.

b only the declaration is not initialized, so typeof (b) is undefined.

c is undefined, so alert (c) will error.

3. Write JavaScript code to merge two arrays and delete the second element.

Combine JS arrays with the Concat method, Array1.concat (array2).

Delete elements using the Splice method, splice, function prototype splice (INDEX,COUNT), which deletes 1 elements from the array index 1, deletes the second element.

4. A brief description of the scope and closure of JavaScript

The scope of the JS variable is that the local variables defined within the function are valid only within this function, and global variables can be globally valid.

Closure is the ability to change the scope of local variables, save the value, but if used improperly can cause the variable can not be recycled, causing performance problems, or even crashes.

5. Enumerate the JavaScript frameworks you've used, and describe their pros and cons

JS frame: JQuery Easyui, ExtJS, Bootstrap, Angularjs and so on.

jquery Easyui: A lightweight web front-end UI development framework, especially suited to the interface development of MIS systems, and the ability to reuse jquery plugins.

ExtJS: A unified front-end UI development framework that is moderately difficult to learn. Especially suitable for MIS system interface development, development documentation and example code are more complete. The disadvantage is a large number of JS scripts, reducing the speed of operation.

Bootstrap: Responsive Web development Framework, the advantage is to reduce the back-end developers to develop front-end page difficulty, unified interface style, the disadvantage is that the interface style is relatively single.

AngularJS: Introduce the excellent features of Java backend into JS front-end, chatty framework. The disadvantage is that the learning curve is high and Angular2 is almost rewritten.

6. Brief introduction of A. What is the difference between Equals (b) and a==b?

The Equals method compares the content (the value is equal), = = compares the reference address (whether it points to the same object).

7, ASP. What is the difference between application, Session, Cookie, viewstate, and cache variables?

Application application level

Session-level user tracking

Cookie Client stores a small amount of information

ViewState mechanism for maintaining the state of the ASP.

Cache caching

8. There are several types of return values for the enumeration of ASP. ActionResult?

There are several types of view (view), Partialview (partial view), content (contents), JSON (JSON string), Javascript (JS script), file (files).

9. Briefly describe the advantages of ASP. NET Webapi vs. ASP.

The WEBAPI message processing pipeline is independent of the ASP. NET platform and supports multiple boarding methods.

10. Describe the life cycle of the ASP.

The user requests the application resource from the WEB server->asp.net receives the first request to the application, and creates an ASP. NET core object for each request, and assigns the HttpApplication object to the request, Processing requests by the HttpApplication pipeline

refer:https://msdn.microsoft.com/zh-cn/library/ms178473 (v=vs.100). aspx

11. What are the similarities and differences between delay loading and direct loading in ORM?

Deferred loading (lazy Loading) can reduce unnecessary overhead by loading data only when data is really needed.

12, briefly describe the difference between func<t> and action<t>?

Func<t> is a delegate with a return value,action<t> is a delegate that has no return value.

13. How to open an asynchronous thread? What are the considerations when multithreaded programming?

APM (Asynchrocous programming Model, for example: BeginXXX, IAsyncResult), EAP (event-based asynchronous Pattern, For example: Downloadcontentasync), TPL (Task Parallel Library, such as: Task.Factory.StartNew), async/await.

Thread starvation, thread deadlock, thread synchronization, thread safety.

14. What is LINQ and how LINQ works? and write a sample code for LINQ to Object

LINQ (Language Integrated Query), where LINQ to object is a call to a enumberable extension method that is converted to lambda and executed when executed.

Sample code: LINQ Grouping statistics

var  from inch  Selectnew= g.sum (p = = = ":"  +

15. What are the characteristics of object-oriented? How do you understand that?

Inheritance (inheritance), Encapsulation (encapsulation), polymorphism (polymorphism).

16. List the design patterns you know? What have you used in a real project? What's your experience?

Singleton mode, template method, Factory mode, appearance mode, strategy mode, etc.

17, write SQL from a table to identify the name field to repeat more than three records, and write SQL to delete these duplicate records

Query Name field records repeat more than three records

Select name from A group by name has count (name) >3
Delete duplicate records

if exists(Select *  fromsysobjectswhereName= 'Tempa')Drop TableTempaSelectRow_number () Over(Order  byName) asROWID, Name intoTempa fromASelect *  fromTempa--delete duplicate records, keep only the rowid the smallest lineDelete  fromTempawhereNameinch(SelectName fromTempaGroup  byName having Count(name)>3) androwID not inch(Select min(ROWID) fromTempaGroup  byName having Count(name)>3)Select *  fromTempa

. Net Face Questions Summary (v)