🌐 Output to the command line using Node.js
🌐 Basic output using the console module
Node.js 提供了一个 console 模块，它提供了许多与命令行交互的非常有用的方法。
🌐 Node.js provides a console module which provides tons of very useful ways to interact with the command line.
它基本上与浏览器中找到的 console 对象相同。
🌐 It is basically the same as the console object you find in the browser.
最基本和最常用的方法是 console.log()，它会将你传给它的字符串打印到控制台上。
🌐 The most basic and most used method is console.log(), which prints the string you pass to it to the console.
如果你传递一个对象，它会将其渲染为字符串。
🌐 If you pass an object, it will render it as a string.
你可以向 console.log 传递多个变量，例如：
🌐 You can pass multiple variables to console.log, for example:
const x = 'x';
const y = 'y';
console.log(x, y);Node.js 将打印两者。
🌐 and Node.js will print both.
我们还可以通过传递变量和格式说明符来格式化漂亮的短语。
🌐 We can also format pretty phrases by passing variables and a format specifier.
例如：
🌐 For example:
console.log('My %s has %d ears', 'cat', 2);%s将变量格式化为字符串%d将变量格式化为数字%i仅将变量格式化为整数部分%o将变量格式化为对象
示例：
🌐 Example:
console.log('%o', Number);🌐 Clear the console
console.clear() 会清空控制台（具体行为可能取决于所使用的控制台）
🌐 Counting elements
console.count() 是一个非常方便的方法。
拿这个代码：
🌐 Take this code:
const x = 1;
const y = 2;
const z = 3;
console.count(
'The value of x is ' + x + ' and has been checked .. how many times?'
);
console.count(
'The value of x is ' + x + ' and has been checked .. how many times?'
);
console.count(
'The value of y is ' + y + ' and has been checked .. how many times?'
);发生的情况是，console.count() 会计算某个字符串被打印的次数，并在旁边显示计数：
🌐 What happens is that console.count() will count the number of times a string is printed, and print the count next to it:
你可以只计算苹果和橘子：
🌐 You can just count apples and oranges:
const oranges = ['orange', 'orange'];
const apples = ['just one apple'];
oranges.forEach(fruit => {
console.count(fruit);
});
apples.forEach(fruit => {
console.count(fruit);
});🌐 Reset counting
console.countReset() 方法重置与 console.count() 一起使用的计数器。
🌐 The console.countReset() method resets counter used with console.count().
我们将使用苹果和橙子示例来演示这一点。
🌐 We will use the apples and orange example to demonstrate this.
const oranges = ['orange', 'orange'];
const apples = ['just one apple'];
oranges.forEach(fruit => {
console.count(fruit);
});
apples.forEach(fruit => {
console.count(fruit);
});
console.countReset('orange');
oranges.forEach(fruit => {
console.count(fruit);
});注意 console.countReset('orange') 调用是如何将计数器的值重置为零的。
🌐 Notice how the call to console.countReset('orange') resets the value counter to zero.
🌐 Print the stack trace
在某些情况下，打印函数的调用栈跟踪可能会很有用，也许是为了回答“你是怎么到达代码的这一部分的？”这个问题。
🌐 There might be cases where it's useful to print the call stack trace of a function, maybe to answer the question how did you reach that part of the code?
你可以使用 console.trace() 来实现这一点：
🌐 You can do so using console.trace():
const function2 = () => console.trace();
const function1 = () => function2();
function1();这将打印堆栈跟踪。如果我们在 Node.js REPL 中尝试，会打印出如下内容：
🌐 This will print the stack trace. This is what's printed if we try this in the Node.js REPL:
Trace
at function2 (repl:1:33)
at function1 (repl:1:25)
at repl:1:1
at ContextifyScript.Script.runInThisContext (vm.js:44:33)
at REPLServer.defaultEval (repl.js:239:29)
at bound (domain.js:301:14)
at REPLServer.runBound [as eval] (domain.js:314:12)
at REPLServer.onLine (repl.js:440:10)
at emitOne (events.js:120:20)
at REPLServer.emit (events.js:210:7)🌐 Calculate the time spent
你可以使用 time() 和 timeEnd() 轻松计算一个函数运行所需的时间
🌐 You can easily calculate how much time a function takes to run, using time() and timeEnd()
const doSomething = () => console.log('test');
const measureDoingSomething = () => {
console.time('doSomething()');
// do something, and measure the time it takes
doSomething();
console.timeEnd('doSomething()');
};
measureDoingSomething();🌐 stdout and stderr
正如我们所见，console.log 非常适合在控制台中打印信息。这就是所谓的标准输出，或 stdout。
🌐 As we saw console.log is great for printing messages in the Console. This is what's called the standard output, or stdout.
console.error 会输出到 stderr 流。
它将显示在控制台中，但可以与常规输出分开处理。
🌐 It will appear in the console, but can be handled separately from regular output.
🌐 Color the output
注意 该资源部分是基于版本 22.11 设计的，该版本将
styleText标记为“活跃开发中”。
在许多情况下，你会倾向于粘贴某些文本以在终端上获得不错的输出。
🌐 In many cases, you will be tempted to paste certain text to get a nice output at the terminal.
node:util 模块提供了一个 styleText 函数。让我们来了解如何使用它。
🌐 There is a styleText function provided by the node:util module. Let's discover how to use it.
首先，你需要从 node:util 模块中导入 styleText 函数：
🌐 First of all, you need to import the styleText function from the node:util module:
import { styleText } from 'node:util';然后，你可以使用它来设置文本样式：
🌐 Then, you can use it to style your text:
console.log(
styleText(['red'], 'This is red text ') +
styleText(['green', 'bold'], 'and this is green bold text ') +
'this is normal text'
);第一个参数是样式数组，第二个参数是你想要设置样式的文本。我们邀请你阅读文档
🌐 The first argument is an array of styles, and the second argument is the text you want to style. We invite you to read the docs