Node.js process.emitWarning() 方法
process.emitWarning()方法是流程模块的内置应用程序编程接口，用于发送自定义或特定于应用程序的流程警告。
句法：
process.emitWarning(warning[, options])参数：此函数接受以下参数：
- 警告：用于表示要发出的警告。
- options：它是一个可选参数，它可以具有以下属性：
- type：用于表示警告为字符串形式时发出的警告类型。
- code：用于表示发出的警告实例的唯一标识符。
- ctor：这是一个可选函数，用于在警告为字符串形式时限制生成的堆栈跟踪。
- detail：用于添加附加文本以包含在错误中。
返回值：此事件只返回一个回调函数以供进一步操作。
示例 1： process.emitWarning()方法在侦听进程时将 Error 对象传递给警告处理程序。
index.js
console.log("Start ...");
// Use setInterval to keep the process running
setInterval(() => {
console.log("Working ...");
}, 1000);
setTimeout(() => {
process.emitWarning('Something happened!', {
code: 'Custom_Warning',
detail: 'Additional information about warning'
});
}, 4000);
// Start listening to the process
process.on('warning', (warning) => {
// If there is a warning then print
// it and stop the process
if (warning) {
console.log(warning);
process.exit(0);
}
});index.js
console.log("Start ...");
// Use setInterval to keep the process running
setInterval(() => {
console.log("Working ...");
}, 1000);
setTimeout(() => {
process.emitWarning('Something happened!', {
code: 'Custom_Warning',
detail: 'Additional information about warning'
});
}, 4000);
setTimeout(() => {
process.emitWarning('Something needs to be fixed!', {
type: 'IMPORTANT',
code: '007',
detail: 'Can not proceed further!'
});
}, 6000);
// Start listening to the process
process.on('warning', (warning) => {
// If there is an important warning
// stop the process
// warning.name = type
if (warning.name === 'IMPORTANT') {
console.log('Fix this ASAP!')
process.exit(0);
}
});index.js
console.log("Start ...");
// Use setInterval to keep the process running
setInterval(() => {
console.log("Working ...");
}, 1000);
setTimeout(() => {
process.emitWarning(new Error('Whoops!'), {
code: 'Custom_Warning',
detail: 'Additional information about warning'
});
}, 4000);
// Start listening to the process
process.on('warning', (warning) => {
// If there is a warning then print
// it and stop the process
if (warning) {
console.warn(warning);
process.exit(0);
}
});使用以下命令运行index.js文件：
node index.js输出：
Start …
Working …
Working …
Working …
(node:12621) [Custom_Warning] Warning: Something happened!
Additional information about warning
(Use `node –trace-warnings …` to show where the warning was created)
Warning: Something happened!
at Timeout._onTimeout (/home/aditya/Programming/GFG/New/EmitWarning.js:9:13)
at listOnTimeout (node:internal/timers:556:17)
at processTimers (node:internal/timers:499:7) {
code: ‘Custom_Warning’,
detail: ‘Additional information about warning’
}
示例 2：发出多个警告并根据警告类型采取措施。
index.js
console.log("Start ...");
// Use setInterval to keep the process running
setInterval(() => {
console.log("Working ...");
}, 1000);
setTimeout(() => {
process.emitWarning('Something happened!', {
code: 'Custom_Warning',
detail: 'Additional information about warning'
});
}, 4000);
setTimeout(() => {
process.emitWarning('Something needs to be fixed!', {
type: 'IMPORTANT',
code: '007',
detail: 'Can not proceed further!'
});
}, 6000);
// Start listening to the process
process.on('warning', (warning) => {
// If there is an important warning
// stop the process
// warning.name = type
if (warning.name === 'IMPORTANT') {
console.log('Fix this ASAP!')
process.exit(0);
}
});
使用以下命令运行index.js文件：
node index.js输出：
Start …
Working …
Working …
Working …
(node:12893) [Custom_Warning] Warning: Something happened!
Additional information about warning
(Use `node –trace-warnings …` to show where the warning was created)
Working …
Working …
(node:12893) [007] IMPORTANT: Something needs to be fixed!
Can not proceed further!
Fix this ASAP!
示例 3：将 Error 对象作为警告而不是字符串传递。请注意，如果正在传递 Error 对象，那么可选参数将被忽略。
index.js
console.log("Start ...");
// Use setInterval to keep the process running
setInterval(() => {
console.log("Working ...");
}, 1000);
setTimeout(() => {
process.emitWarning(new Error('Whoops!'), {
code: 'Custom_Warning',
detail: 'Additional information about warning'
});
}, 4000);
// Start listening to the process
process.on('warning', (warning) => {
// If there is a warning then print
// it and stop the process
if (warning) {
console.warn(warning);
process.exit(0);
}
});
使用以下命令运行index.js文件：
node index.js输出：
Start …
Working …
Working …
Working …
(node:13232) Error: Whoops!
(Use `node –trace-warnings …` to show where the warning was created)
Error: Whoops!
at Timeout._onTimeout (/home/aditya/Programming/GFG/New/EmitWarning.js:9:25)
at listOnTimeout (node:internal/timers:556:17)
at processTimers (node:internal/timers:499:7)
参考： https://nodejs.org/api/process.html#process_process_emitwarning_warning_type_code_ctor