On the one hand, most of the questions are not of high quality. On the other hand, there are few answers. Even if you get the interview questions, it will not help you much.
Recently, I spent some time for you to sort out the 2020 first – and second-tier Internet companies, including JavaScript, algorithm, network & security, Vue, React and a large number of front-end knowledge points and related interview questions. The answer and analysis are also sorted in the article, sorting is not easy, please pass by the strong man to star, if you can star fork watch three even better, thank you 😄 🙏
Because of the length, this article includes the first 50, the last 50 will be updated in the next article, welcome to follow.
1. Write mySetInterVal(fn, a, b) for each interval a,a+b,a+2b, and then write myClear to stop mySetInterVal above
Company: Headline
Classification: JavaScript
Answer:
2. Merge two dimensional ordered numbers to form one dimensional ordered array, merge sort idea
Company: Headline
Classification: Algorithms
Answer:
3. Fibonacci series
Companies: Tencent, CVTE, Microsoft
Classification: Algorithms
Answer:
4. The maximum length of the string that is not repeated
Company: Tencent
Classification: Algorithms
Answer:
5. This section describes the versions of Chrome
Company: Didi
Category: Network & Security
Answer:
6. What details can be optimized in React project? What performance optimizations have been made in actual development
Companies: Didi, One to one, netease, Youzan, Hujiang, Ximalaya, Kujiale, Kuaishou
Classification: the React
Answer:
7. What did the latest version of React fix and add
Company: Didi
Classification: the React
Answer:
8. Describe Http caching policies. What are the differences and what problems do they solve
Company: Didi, tiaotiao, netease, Easy car, Pulse, one on one, hupu, dig money, love fan son
Category: Network & Security
Answer:
9. Introduce the principle, difference and application of anti-shake throttling, and implement it with JavaScript
Companies: Didi, Hupu, Wacai, 58, Toutiao
Category: JavaScript, programming questions
Answer:
10. Front-end security, man-in-the-middle attack
Company: Didi
Category: Network & Security
Answer:
11. On closures, why use closures? Explain how closures work and how they can be used
Companies: Didi, Ctrip, Ximalaya, Weici, Mogujie, Kujialuo, Tencent Appao, Anjuke
Classification: JavaScript
Answer:
12. CSS pseudo-classes and pseudo-elements
Company: Didi
Classification: Css
Answer:
13. Have a bunch of round numbers, divide them into three parts and make sure each part is as equal as possible (11, 42, 23, 4, 5, 6, 4, 5, 6, 4, 5, 6, 11, 23, 42, 56, 78, 90)
Company: Didi
Classification: Algorithms
Answer:
14. Implement _. Get for lodash
Company: Didi
Classification: JavaScript
Answer:
15. Realize the add (1) (2) (3)
Company: Didi
Classification: JavaScript
Answer:
16. Implement chained calls
Company: Didi
Classification: JavaScript
Answer:
React event binding principle
Companies: Didi, Hujiang
Classification: the React
Answer:
18. What is the difference between array-like and array-like
Company: Hikvision
Classification: JavaScript
Answer:
19. What optimizations webPack has made, in terms of development efficiency, packaging strategy, etc
Company: Didi, Kuaishou, one to one, high thought education
Classification: engineering
Answer:
20. Event loops (Node, browser)
Companies: Didi, Companion Fish, Autonavi, Freely, Hupu, 58
Category: Node, JavaScript
Answer:
21. How to encapsulate Node middleware
Companies: Didi, Kugou
Classification: the Node
Answer:
22. How does the node middle tier do the request merge and forward
Company: easy car
Classification: the Node
Answer:
23. Introduce the features, advantages and disadvantages of promise, and how to implement the promise internally
Companies: Didi, Tiaotiao, Himalaya, Taeba, Secu, Percentile, 58, Anjuke
Category: JavaScript, programming questions
Answer:
24. Realize the Promise. All
Promise.all = function (arr) {
// Implementation code
};
Copy the codeCompanies: Didi, Tiaotiao, Youzhan, Weidoctor
Category: JavaScript, programming questions
Answer:
25.React component communication mode
Companies: Didi, One to one, Himalaya, Mogujie
Classification: the React
Answer:
26. Comparison of Redux-Saga and Mobx
Company: one on one
Classification: the React
Answer:
27. Tell me about react-fiber
Company: headline, drip, cainiao network, dig money, Himalaya
Classification: the React
Answer:
28. Publish and subscribe by hand
Companies: Didi, Toutiao
Classification: JavaScript
Answer:
29. Write array to tree
Company: Didi
Classification: JavaScript
Answer:
30. How to access arR [-1] using ES6proxy
Company: Didi
Classification: JavaScript
Answer:
31. Write the result of the following code execution
console.log(1);
setTimeout((a)= > {
console.log(2);
process.nextTick((a)= > {
console.log(3);
});
new Promise((resolve) = > {
console.log(4);
resolve();
}).then((a)= > {
console.log(5);
});
});
new Promise((resolve) = > {
console.log(7);
resolve();
}).then((a)= > {
console.log(8);
});
process.nextTick((a)= > {
console.log(6);
});
setTimeout((a)= > {
console.log(9);
process.nextTick((a)= > {
console.log(10);
});
new Promise((resolve) = > {
console.log(11);
resolve();
}).then((a)= > {
console.log(12);
});
});
Copy the codeClassification: JavaScript
Answer:
32. Write the execution result
function side(arr) {
arr[0] = arr[2];
}
function a(a, b, c = 3) {
c = 10;
side(arguments);
return a + b + c;
}
a(1.1.1);
Copy the codeClassification: JavaScript
Answer:
33. Write the results of the execution
var min = Math.min();
max = Math.max();
console.log(min < max);
Copy the codeClassification: JavaScript
Answer:
34. Write the results and explain why
var a = 1;
(function a () {
a = 2;
console.log(a); }) ();Copy the codeClassification: JavaScript
Answer:
35. Write the result and explain why
var a = [0];
if (a) {
console.log(a == true);
} else {
console.log(a);
}
Copy the codeClassification: JavaScript
Answer:
36. Write the results and explain why
(function () {
var a = (b = 5); }) ();console.log(b);
console.log(a);
Copy the codeClassification: JavaScript
Answer:
37. Write the results and explain why
var fullname = 'a';
var obj = {
fullname: 'b'.prop: {
fullname: 'c'.getFullname: function() {
return this.fullname; }}};console.log(obj.prop.getFullname()); // c
var test = obj.prop.getFullname;
console.log(test()); // a
Copy the codeClassification: JavaScript
Answer:
38. Write the result and explain why
var company = {
address: 'beijing'
}
var yideng = Object.create(company);
delete yideng.address
console.log(yideng.address);
Copy the codeClassification: JavaScript
Answer:
39. Write the results and explain why
var foo = function bar(){ return 12; };
console.log(typeof bar());
Copy the codeClassification: JavaScript
Answer:
40. Write the result and explain why
var x=1;
if(function f(){}){
x += typeof f;
}
console.log(x)
Copy the codeClassification: JavaScript
Answer:
41. Write the result and explain why
function f(){
return f;
}
console.log(new f() instanceof f);
Copy the codeClassification: JavaScript
Answer:
42. Write the result and explain why
var foo = {
bar: function(){
return this.baz;
},
baz:1
}
console.log(typeof (f=foo.bar)());
Copy the codeClassification: JavaScript
Answer:
43. Describe the problems and reasons that should be paid attention to during the development of React Hooks.
Answer:
44. Does the name option in the Vue component serve any other purpose than keep-alive? Can you tell me what you know about keep-alive? (usually used and source code implementation)
Classification: Vue
Answer:
45. Why does Vue use vm.$set() to solve the problem of the object not responding to new attributes? Can you explain how the following code works?
Vue.set (object, propertyName, value)
vm.$set (object, propertyName, value)
Copy the codeClassification: Vue
Answer:
46. Since Vue can accurately detect changes in the specific DOM through data hijacking, why do you need virtual DOM diff?
Classification: Vue
Answer:
47. What is true about the advantages and disadvantages of vue.js virtual DOM? (pops)
A. A performance lower limit is guaranteed, which is much better than rough DOM manipulation, so the framework’s virtual DOM at least ensures that you can still provide decent performance without having to manually optimize. B. There is no need to manually operate the DOM, only need to write the code logic of view-Model, the framework will help us to update the View in a predictable way according to the virtual DOM and data two-way binding, greatly improving our development efficiency; C. Extreme optimization: Virtual DOM + reasonable optimization can achieve extreme performance D. It can be cross-platform. Virtual DOM is essentially a JavaScript object, while DOM is strongly related to the platform. In contrast, virtual DOM can be more easily operated across platforms, such as server rendering, WEEX development, and so on.
Classification: Vue
Answer:
48. What does the following code output?
for (let i = 0; i < 3; i++) {
setTimeout((a)= > console.log(i), 1);
}
Copy the codeClassification: JavaScript
Answer:
49. Write the result and explain why
const num = {
a: 10,
add() {
return this.a + 2;
},
reduce: (a)= > this.a 2 -;
};
console.log(num.add());
console.log(num.reduce());
Copy the codeClassification: JavaScript
Answer:
50. Write the result and explain why
const person = { name: "yideng" };
function sayHi(age) {
return `The ${this.name} is ${age}`;
}
console.log(sayHi.call(person, 5));
console.log(sayHi.bind(person, 5));
Copy the codeClassification: JavaScript
Answer:
Front brush problem artifact
Not enough for these problems? Scan the code to enter the front interview planet 🌍, unlock the brush question artifact, but also can obtain 800+ front end test questions and a line of common interview high-frequency test points.
