4399 2019 front-end pen questions

Disclaimer

Questions about this blog post from 4399 Campus Recruitment 2019, for reference, if infringement, please inform deleted!

[A]
AD is not the right way to load resources. http https compatible, which is to support https protocol to access the link also supports the http protocol access, not vice versa.

[A]
sessionStorage and localStorage can do localized storage, which can reach the size of 5K;
the cookie is often used as transmission between client and server, its size can not exceed 4k, easy to transport;
sessionStorage the life cycle of the current browser window is closed after the failure of the browser; localStorage life cycle is perpetual, unless cleared manually.

The following C language program, the final output is

main(){
     int i=0,s=0;
     for (;;){
         if(i==4)continue;
 		if (i5)break;
         i++;
         s+=i;
     }
    printf("%d\n",s);
}

15 A.
B. 2
C. 10
D. endless loop

The following code is run results

var game='4399'
game.substring(2,1)
console.log(game)

A. 4

B. 3

C. 4399

D. 9

localstorage with cookie What are the differences (answer two kinds)? Use localstorage what needs attention?
How to optimize front-end website performance?

Use front-end cache localstorage implement the following two methods to cache user title browsing history, localstoragetitle title_history use this key.
```
function get() //获取历史标题列表;返回一个数组
function addtitle() //增加一个标题记录
```
Suppose there is a string s, and a length of up to 1000, write function palindrome found in the string of characters longest palindromic fragment.

Example 1: s is cdcde ", output: cdc, Note:" dcd also a valid value.

Example 2: s is "cdde", the output "dd

Note: If the time is not enough, you can list the problem-solving ideas, as appropriate to the sub.
Page includes a div, id is Rotate, Red background color, width 200px, 100px height click on the div, div starts to rotate, the rotation speed of the click stop button clicks again, the rotational speed decreases div (html + css + js)

Tip: Use requestanimationframe

Nearly two years, what is the biggest problem you encountered? How did you locate and solve the problem?
University of the past few years they have established what kind of goals? What about reached? Why?
What is your biggest weakness? Or do you think the next 35 years are most likely to hinder what personality factors that you grew up is?
Please describe an example, you have solved a technical problem can not be resolved other students, how do you do it?
If you and your colleagues are assigned to a mission of two modules, he did not fully understand his module, and if you do change his very efficient module will be completed soon, how would you do?

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