process.emitWarning(warning[, options])

• warning <string> | <Error> 触发的警告。
• options <Object>
  • type <string> 当 warning 是一个 String 时，则 type 是用于被触发的警告类型的名称。 默认值: 'Warning'。
  • code <string> 要触发的警告实例的唯一标识符。
  • ctor <Function> 当 warning 是一个 String 时，则 ctor 是一个可选的函数，用于限制生成的堆栈信息。默认值: process.emitWarning。
  • detail <string> 错误的附加信息。

process.emitWarning() 方法可用于触发自定义或应用特定的进程警告。 可以通过给 'warning' 事件增加句柄来监听这些警告。

// 使用代码和其他详细信息触发警告。
process.emitWarning('出错啦', {
  code: 'MY_WARNING',
  detail: '一些额外的信息'
});
// 触发:
// (node:56338) [MY_WARNING] Warning: 出错啦
// 一些额外的信息

在上面例子中， process.emitWarning() 内部生成了一个 Error 对象，并传给 'warning' 句柄。

process.on('warning', (warning) => {
  console.warn(warning.name);    // 'Warning'
  console.warn(warning.message); // '出错啦'
  console.warn(warning.code);    // 'MY_WARNING'
  console.warn(warning.stack);   // Stack trace
  console.warn(warning.detail);  // '一些额外的信息'
});

如果 warning 是一个 Error 对象，则 options 参数会被忽略。

• warning <string> | <Error> The warning to emit.
• options <Object>
  • type <string> When warning is a String, type is the name to use for the type of warning being emitted. Default: 'Warning'.
  • code <string> A unique identifier for the warning instance being emitted.
  • ctor <Function> When warning is a String, ctor is an optional function used to limit the generated stack trace. Default: process.emitWarning.
  • detail <string> Additional text to include with the error.

The process.emitWarning() method can be used to emit custom or application specific process warnings. These can be listened for by adding a handler to the 'warning' event.

// Emit a warning with a code and additional detail.
process.emitWarning('Something happened!', {
  code: 'MY_WARNING',
  detail: 'This is some additional information'
});
// Emits:
// (node:56338) [MY_WARNING] Warning: Something happened!
// This is some additional information

In this example, an Error object is generated internally by process.emitWarning() and passed through to the 'warning' handler.

process.on('warning', (warning) => {
  console.warn(warning.name);    // 'Warning'
  console.warn(warning.message); // 'Something happened!'
  console.warn(warning.code);    // 'MY_WARNING'
  console.warn(warning.stack);   // Stack trace
  console.warn(warning.detail);  // 'This is some additional information'
});

If warning is passed as an Error object, the options argument is ignored.