2021 jd.com written examination summary

This article was not intended to be written by rookies , But I feel that the problems encountered still need to be solved , So write it down

Every item in the web page is DOM A node object on the tree , All nodes contain attributes such as

1. nodeType
2. nodeScope
3. nodeValue
4. nodeName

The rookie searched , It seems that there is something wrong with the title , Because this is a single choice question ！

I feel that the topic should be chosen not to belong to ！

The status is described as ：Server Unavailable, The server is currently unable to process the client's request , It may return to normal after some time , Its status code is

1. 403
2. 404
3. 503
4. 500

answer ：503

This rookie can only say , Recite and understand the return code , Sao Nian ！ The rookie may not have done it before , Now as long as it's not particularly difficult , Basically no problem , Advice to see ：《 The illustration Http》 A Book , Or directly Novice tutorial ！

In the internal sorting method based on comparison , The comparison times are independent of the initial sorting state of the records to be sorted

1. Quick sort
2. Bubble sort
3. Bisection insertion sort
4. Insertion sort

answer ：？

Rookies are not up to scratch , Sorting knows a two-level cycle , I don't know exactly , Wait for the novice to finish watching js The algorithm and data structure of , Now readers can only solve it by themselves

Reference resources ： Sorting algorithm Baidu

Binary files commonly used in system management , Under what directory is it usually placed

1. /usr/bin
2. /usr/sbin
3. /sbin
4. /root

answer ：/usr/bin

DOM Provides a representation of the tree structure , The following description is correct

1. Not all HTML element All are element nodes
2. stay HTML element Internal text The content is also text node
3. Document Is not a document node, Is a node format
4. be-all comments All are document node

answer ： stay HTML element Internal text The content is also text node

About Http Request method GET and POST Differences between request schemes , The statement is wrong

1. GET The parameters are generally determined by URL Pass on , and POST The parameters of are generally placed in Request body in
2. POST request URL Parameters in will not be resolved
3. GET The request will be initiated by the browser cache
4. GET Than POST It's not safe , Because the parameters are directly exposed to URL On , So it can't be used to convey sensitive information

Idempotent understanding ： Deep understanding of idempotency

answer ：POST request URL Parameters in will not be resolved

This should be parsed , Rookies don't know very well , Reference resources ：Post Method parameters are written in body Neutralization is written in url What's the difference between ？ You know

POST Method how to segment header and body information

1. \r
2. \r\n\r\n
3. \r\n
4. \n
   
   
   
   answer ：\r\n

href、src、a label

1. Labeled src Property is used to specify the address to link
2. Tags are page link tags , It can only be used to link to other pages
3. Tags are page link tags , It can only be used to link to other places on this page
4. Labeled href Property is used to specify the address to link

href Property is used to specify the URL,src Property specifies the location of the external resource （URL).a The tag can be linked to the outside or jump to other places on this page , therefore 2,3 error ！

answer ： Labeled src Property is used to specify the address to link

If the linear programming problem has an optimal solution , Then the optimal solution must not be

1. Within the feasible region
2. None of the other options are right
3. On an edge of the feasible region
4. On a vertex of the feasible region

answer ：？

This rookie doesn't know , I hope the readers , Define the , Encouraging words ！

Undirected graph

answer ：？

This rookie doesn't know , I hope the readers , Define the , Encouraging words ！

Code running problem 1

var setObj = function(o){
    
  o.name = " mary";
}
var p = {
    name:" john",age:24};
setObj(p);
console.log(p.name);
console.log(p.age);

answer ：
mary
24

Code running problem 2

Let the reader run it by himself , Rookie company c There are no compilers for languages , Ha ha ha ！

summary

Finish JD's written exam , I feel like I don't know anything , Just ask JD to be a person ！ The rookie is just a garbage front end , Really not c Language ！

I feel that the college is indeed deserted , Patronize the front end of learning , Did not pay attention to the foundation , And the front-end is not very solid , Because it's always fun , Readers are expected to find a good job ！

Here are suggestions ： The experience of computer senior