process.exit([code])

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新增于: v0.1.13

code <integer> 退出码。默认值: 0。

process.exit() 方法以退出状态 code 指示 Node.js 同步地终止进程。如果省略 code，则使用成功代码 0 或 process.exitCode 的值（如果已设置）退出。在所有的 'exit' 事件监听器被调用之前，Node.js 不会终止。

使用失败代码退出：

process.exit(1);

执行 Node.js 的 shell 可以看到退出码为 1。

调用 process.exit() 会强制进程尽快退出，即使还有尚未完全完成的异步操作在等待，包括对 process.stdout 和 process.stderr 的 I/O 操作。

在大多数情况下，实际上不需要显式地调用 process.exit()。如果事件循环中没有待处理的额外工作，则 Node.js 进程会自行退出。 process.exitCode 属性可以设置来告诉进程使用什么退出码（当进程正常退出时）。

例如，以下示例描述了 process.exit() 方法的错误用法，这可能会导致打印到 stdout 的数据被截断和丢失：

// 这是一个错误用法的示例：
if (someConditionNotMet()) {
  printUsageToStdout();
  process.exit(1);
}

这个问题的原因是因为 Node.js 中的 process.stdout 的写入有时是异步的，并且可能发生在 Node.js 事件循环的多个时间点。但是，调用 process.exit() 会强制进程退出（在这些额外的 stdout 写入操作被执行之前）。

代码不应直接调用 process.exit()，而应设置 process.exitCode 并允许进程自然地退出（避免为事件循环调度任何额外的工作）：

// 如何正确地设置退出码，同时让进程正常地退出。
if (someConditionNotMet()) {
  printUsageToStdout();
  process.exitCode = 1;
}

如果由于错误条件而需要终止 Node.js 进程，则抛出未捕获的错误并允许进程相应地终止，这比调用 process.exit() 更安全。

在 Worker 线程中，此函数会停止当前线程（而不是当前进程）。

Added in: v0.1.13

code <integer> The exit code. Default: 0.

The process.exit() method instructs Node.js to terminate the process synchronously with an exit status of code. If code is omitted, exit uses either the 'success' code 0 or the value of process.exitCode if it has been set. Node.js will not terminate until all the 'exit' event listeners are called.

To exit with a 'failure' code:

process.exit(1);

The shell that executed Node.js should see the exit code as 1.

Calling process.exit() will force the process to exit as quickly as possible even if there are still asynchronous operations pending that have not yet completed fully, including I/O operations to process.stdout and process.stderr.

In most situations, it is not actually necessary to call process.exit() explicitly. The Node.js process will exit on its own if there is no additional work pending in the event loop. The process.exitCode property can be set to tell the process which exit code to use when the process exits gracefully.

For instance, the following example illustrates a misuse of the process.exit() method that could lead to data printed to stdout being truncated and lost:

// This is an example of what *not* to do:
if (someConditionNotMet()) {
  printUsageToStdout();
  process.exit(1);
}

The reason this is problematic is because writes to process.stdout in Node.js are sometimes asynchronous and may occur over multiple ticks of the Node.js event loop. Calling process.exit(), however, forces the process to exit before those additional writes to stdout can be performed.

Rather than calling process.exit() directly, the code should set the process.exitCode and allow the process to exit naturally by avoiding scheduling any additional work for the event loop:

// How to properly set the exit code while letting
// the process exit gracefully.
if (someConditionNotMet()) {
  printUsageToStdout();
  process.exitCode = 1;
}

If it is necessary to terminate the Node.js process due to an error condition, throwing an uncaught error and allowing the process to terminate accordingly is safer than calling process.exit().

In Worker threads, this function stops the current thread rather than the current process.