2018 latest front-end interview questions three-JS Tutorial-php.cn

This time we bring you the latest front-end interview questions in 2018. We know that interviews are an essential part of front-end work. This time, the common front-end interview questions are sorted and summarized to help you get through the front-end interview. Big trouble. Let’s take a look.

【Related recommendations:Front-end interview questions(2020)】

In the process of making a web application or website, how do you consider its UI, security, performance, SEO, maintainability and technical factors?

1 UI:

The interface should be beautiful, have personality, consider the logic of user use and be simple, making it comfortable and free to use. Usage habits should conform to the habits of most users, such as requiring less user input, using selection methods, and providing search and prompt functions.

Second security:

1. Verify the validity of the input (illegal characters,special characters) such as The methodhtmlspecialchars() in PHP converts special characters (>) into html entities, trim() removes unnecessary characters entered by the user, andstripslashes() removes the reverse characters entered by the user. Slash and so on.

and configuration)

4. Buffer overflow;5. Injection attack: Injection attack is the result of the application violating the "principle of separation of data and code". It has two conditions: first, the user can control the input of data; second, the code pieces together the data entered by the user and executes the data as code.

6. Insecure storage; do not use a separate encryption strategy like MD5 or SHA. When hashing password values, use seasoning or multiple seasonings to prevent rainbow attacks. For short passwords, use a short hash algorithm, such as bcrypt or scrypt.

Three high performance:

1. DNS (Domain Name System) load balancing; configure the same domain name for multiple IP addresses in DNS For example: www.baidu.com, so the client querying this domain name will get one of the addresses, allowing different customers to access different servers to achieve load balancing and reduce the pressure on the server. DNS load balancing is a simple and effective method, but it cannot distinguish the differences between servers and cannot reflect the current operating status of the server.2, HTTP redirection (by re -regulating the client, the pressure of dispersion and transfer of requests, such as some download services usually have several mirror servers); 301 redirection is the most feasible one that is the most feasible one. Of these methods, SEO is the most friendly.

3. Distributed cache;

4. Database expansion: read-write separation, vertical partitioning, horizontal partitioning

5. Reverse proxy load balancing: let the proxy server Requests are forwarded evenly to one of multiple internal web servers to achieve load balancing. This proxy method is different from the ordinary proxy method. The standard proxy method is that customers use the proxy to access multiple external Web servers. This proxy method is used by multiple customers to access internal Web servers, so it is also called reverse.

Agent Mode

The advantage of using a reverse proxy is that it can combine load balancing and the proxy server's caching technology to provide beneficial performance and additional security. External customers cannot directly access the real server. And when implemented, a better load balancing strategy can be achieved, and the load can be distributed to internal servers very evenly, without the accidental phenomenon of load being concentrated on a certain server.

Four SEO:

## Select the descriptive language, replace the decorative pictures with text, use h1-h6 reasonably, and correct the pictures Add the alt attribute and the link the target attribute.

Five maintainability:

Is the code easy to understand, is it easy to modify and add new functions, and is the problem code able to be quickly located when a problem occurs.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!