console 控制台

源代码: lib/console.js

console 模块提供了一个简单的调试控制台，类似于网络浏览器提供的 JavaScript 控制台机制。

该模块导出两个特定组件：

• Console 类，具有 console.log()、console.error() 和 console.warn() 等方法，可用于写入任何 Node.js 流。
• 全局的 console 实例，配置为写入 process.stdout 和 process.stderr。 全局的 console 无需调用 require('console') 就可以使用。

警告：全局的控制台对象的方法既不像与其相似的浏览器 API 那样始终同步，也不像所有其他 Node.js 流那样始终异步。 有关更多信息，请参阅进程 I/O 的注意事项。

使用全局的 console 的示例：

console.log('hello world');
// 打印: hello world 到标准输出
console.log('hello %s', 'world');
// 打印: hello world 到标准输出
console.error(new Error('Whoops, something bad happened'));
// 打印错误消息和堆栈跟踪到标准错误：
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// 打印: Danger Will Robinson! Danger! 到标准错误

使用 Console 类的示例：

const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// 打印: hello world 到输出
myConsole.log('hello %s', 'world');
// 打印: hello world 到输出
myConsole.error(new Error('Whoops, something bad happened'));
// 打印: [Error: Whoops, something bad happened] 到错误

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// 打印: Danger Will Robinson! Danger! 到错误

Source Code: lib/console.js

The console module provides a simple debugging console that is similar to the JavaScript console mechanism provided by web browsers.

The module exports two specific components:

• A Console class with methods such as console.log(), console.error() and console.warn() that can be used to write to any Node.js stream.
• A global console instance configured to write to process.stdout and process.stderr. The global console can be used without calling require('console').

Warning: The global console object's methods are neither consistently synchronous like the browser APIs they resemble, nor are they consistently asynchronous like all other Node.js streams. See the note on process I/O for more information.

Example using the global console:

console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr

Example using the Console class:

const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err