node . js process . setuncassetexceptioncapturecallback()方法
原文:https://www . geeksforgeeks . org/node-js-process-setuncassetexceptioncapturecallback-method/
process . setUncaptureexceptioncapturecallback()方法是处理模块的一个内置应用编程接口，用于设置一个回调函数，当发生未捕获的异常时将调用该函数。回调函数将接收异常值作为其第一个参数。
语法:
process.setUncaughtExceptionCaptureCallback( callback_function )
参数:该方法接受如上所述的单个参数，如下所述。
- 回调 _ 函数:这是必选参数。它可以是一个函数或空值。如果设置为 null，那么函数将取消设置回调函数。
返回:不返回值。
以下示例说明了在 Node.js 中使用process . setuncassetexceptioncapturecallback()方法:
例 1:
java 描述语言
// Allocating process module
const process = require('process');
// Function to be set as call back
function to_be_called(ex){
console.log(ex);
}
// Checking whether any callback has been set before calling
// process.setUncaughtExceptionCaptureCallback(to_be_called);
console.log(process.hasUncaughtExceptionCaptureCallback());
// Setting callback
process.setUncaughtExceptionCaptureCallback(to_be_called);
// Checking whether any callback has been set before calling
// process.setUncaughtExceptionCaptureCallback(to_be_called);
console.log(process.hasUncaughtExceptionCaptureCallback());
输出:
false
true
例 2:
java 描述语言
// Allocating process module
const process = require('process');
// Function to be set as call back
function to_be_called(ex) {
console.log(ex);
}
// Checking whether any callback has been set before calling
// process.setUncaughtExceptionCaptureCallback(to_be_called);
// Printing whether a callback is set or not
if (process.hasUncaughtExceptionCaptureCallback()) {
console.log("a callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
} else {
console.log("no callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
}
// Setting callback
if (process.setUncaughtExceptionCaptureCallback) {
process.setUncaughtExceptionCaptureCallback(to_be_called);
} else {
console.log("process.setUncaughtExceptionCaptureCallback() "
+ "method is not defined!");
}
// Checking whether any callback has been set before calling
// process.setUncaughtExceptionCaptureCallback(to_be_called);
if (process.hasUncaughtExceptionCaptureCallback()) {
console.log("a callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
} else {
console.log("no callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
}
// Resetting callback
if (process.setUncaughtExceptionCaptureCallback) {
process.setUncaughtExceptionCaptureCallback(null);
} else {
console.log("process.setUncaughtExceptionCaptureCallback() "
+ " method is not defined!");
}
// Checking whether any callback has been set after resetting
if (process.hasUncaughtExceptionCaptureCallback()) {
console.log("a callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
} else {
console.log("no callback has been set using " +
"process.setUncaughtExceptionCaptureCallback() method");
}
输出:
no callback has been set using process.setUncaughtExceptionCaptureCallback() method
a callback has been set using process.setUncaughtExceptionCaptureCallback() method
no callback has been set using process.setUncaughtExceptionCaptureCallback() method
注意:以上程序将使用节点 filename.js 命令编译运行，仅在 POSIX 平台。
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