How to write nodejs output

Node.js is a very powerful server-side JavaScript programming language that makes writing web applications easier and faster. When you write a Node.js application, output is a very critical step, and here we will introduce you how to output.

Output to the console

Outputting on the console is the most basic output method of Node.js. You can use the built-in console object of Node.js to output content to the console, like this:

console.log('Hello World!');

You can also use console.error() to output error information:

console.error('Oops! Something went wrong!');

In addition, You can also use console.warn() to output warning information:

console.warn('Warning: The system is running low on memory!');

In addition to these, Node.js also provides other methods:

// 清空控制台
console.clear();

// 打印对象信息
console.dir(object);

// 记录时间
console.time('Timer');
for(var i = 0; i < 1000000; i++){}
console.timeEnd('Timer');

Output to a file

In addition to controlling Output on the stage. Under normal circumstances, you may need to output the information to a file, which will facilitate future analysis and maintenance. Here are some ways to output information to a file.

Synchronization method

Use Node.js’s built-in fs (File System) module to perform file reading and writing operations. The following is an example of outputting information to a file:

const fs = require('fs');
fs.writeFileSync('./output.txt', 'Hello World!');

To read the file content, you can use:

const fs = require('fs');
const content = fs.readFileSync('./output.txt');
console.log(content.toString());

Asynchronous method

Use the built-in callback function of Node.js, You can perform operations in parallel. The following is an example of asynchronously outputting information to a file:

const fs = require('fs');
const data = 'Hello World!';
fs.writeFile('./output.txt', data, function (err) {
  if (err) throw err;
  console.log('Data written to file');
});

To read the file content, you can use:

const fs = require('fs');
fs.readFile('./output.txt', function (err, data) {
  if (err) throw err;
  console.log(data.toString());
});

This is the basic operation of Node.js output. Whether you want to output on the console or in a file, Node.js provides you with the corresponding methods to make writing applications easier and more convenient.

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