什么是 stacktrace，如何在 node.js 中打印？

原文:https://www . geeksforgeeks . org/什么是 stacktrace 和如何在节点中打印-js/

Node.js 是一个开源项目，可以用于服务器端脚本。Node.js 是一个跨平台的工具，它允许开发人员在不担心运行时环境的情况下进行编码。Node.js 广泛用于构建动态、轻量级和可扩展的 web 应用程序。Node.js 提供了一个可以用于前端和后端开发的 JavaScript 运行时环境。然而，应用程序经常抛出必须处理的错误或异常。

JVM 会自动显示一个堆栈跟踪，指示在程序执行过程中发生了错误。堆栈跟踪用于在程序执行期间跟踪特定实例上的活动堆栈帧。调试代码时，堆栈跟踪很有用，因为它显示了导致错误的确切点。Node.js 中的错误可以分为四大类:

  • 标准的 JavaScript 错误
  • 系统错误
  • 用户指定的错误
  • 断言错误

Node.js 支持几种机制来传播和处理程序执行过程中出现的错误。所有标准的 JavaScript 错误都会通过抛出一个可以在堆栈跟踪中查看的错误来立即处理。

在 Node.js 中有四种打印堆栈跟踪的方法，它们是:

  • Using error.stack Property: The error.stack property describes the point in the code at which the Error was instantiated.

    语法:

    js error.stack

    示例:

    js console.log("This program demonstrates "             + "stack trace in Node.js"); var err = new Error().stack console.log(err);

    输出:

    ```js This program demonstrates stack trace in Node.js Error at Object. (/home/cg/root/2523129/main.js:20:11) at Module._compile (module.js:570:32) at Object.Module._extensions..js (module.js:579:10) at Module.load (module.js:487:32) at tryModuleLoad (module.js:446:12) at Function.Module._load (module.js:438:3) at Module.runMain (module.js:604:10) at run (bootstrap_node.js:389:7) at startup (bootstrap_node.js:149:9) at bootstrap_node.js:504:3

    ```

  • Using Error.captureStackTrace() Method: This method creates a .stack property on obj that returns a string representing the point in the code at which Error.captureStackTrace(obj) was called. The func parameter represents a function which is optional.

    语法: 错误. captureStackTrace(obj，func)

    示例:

    ```js const obj = {}; Error.captureStackTrace(obj); console.log(obj.stack);

    // Alternatively function MyNewError() {     Error.captureStackTrace(this, MyNewError); }

    console.log(new MyNewError().stack); ```

    输出:

    ```js Error at Object. (/home/cg/root/2523129/main.js:25:13) at Module._compile (module.js:570:32) at Object.Module._extensions..js (module.js:579:10) at Module.load (module.js:487:32) at tryModuleLoad (module.js:446:12) at Function.Module._load (module.js:438:3) at Module.runMain (module.js:604:10) at run (bootstrap_node.js:389:7) at startup (bootstrap_node.js:149:9) at bootstrap_node.js:504:3

    ```

  • Using try-catch block: It is a mechanism of Error Handling and it is used when a piece of code is surrounded in a try block and throw an error to the catch block. If the error is not handled then the program terminates abruptly.

    示例:

    js try {     throw new Error("Error occurred");   } catch(e) {     console.log(e); }

    输出:

    ```js Error at Object. (/home/cg/root/2523129/main.js:25:13) at Module._compile (module.js:570:32) at Object.Module._extensions..js (module.js:579:10) at Module.load (module.js:487:32) at tryModuleLoad (module.js:446:12) at Function.Module._load (module.js:438:3) at Module.runMain (module.js:604:10) at run (bootstrap_node.js:389:7) at startup (bootstrap_node.js:149:9) at bootstrap_node.js:504:3

    ```

  • Using trace command: The console.trace() method is used to display the trace which represents how the code ended up at a certain point.

    示例:

    js console.trace("hello world");

    输出:

    ```js Trace: hello world at Object. (/home/cg/root/2523129/main.js:28:9) at Module._compile (module.js:570:32) at Object.Module._extensions..js (module.js:579:10) at Module.load (module.js:487:32) at tryModuleLoad (module.js:446:12) at Function.Module._load (module.js:438:3) at Module.runMain (module.js:604:10) at run (bootstrap_node.js:389:7) at startup (bootstrap_node.js:149:9) at bootstrap_node.js:504:3

    ```

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