CODEWITHSUNDEEP
node.js
Shivaay
Shivaay

Reputation: 163

How to use Error.captureStackTrace in node.js

Lately I'm going through the implementation of Global Error Handling Middleware in node.js. Then, I came across this Error.captureStackTrace(this,this.constructor).

I have checked the Node documentation & found that - Creates a .stack property on targetObject, which when accessed returns a string representing the location in the code at which Error.captureStackTrace() was called.

MDN Docs - Maintains proper stack trace for where our error was thrown

appError.js File

class AppError extends Error {
constructor(message, statusCode) {
super(message);

this.statusCode = statusCode;

 // Error.captureStackTrace(this, this.constructor);
}}

app.js File

const AppError = require('./appError');
const express = require('express');
const app = express();

app.all('*', (req,res,next) => {
         const custErr = new AppError('Mentioned Route is not available on server','404');
         next();
})

My Observations when I tried to debug the code:

  1. I found that .stack property is available on the custErr object even though I have commented the Error.captureStackTrace(this, this.constructor) in appError.js file.
  2. I'm still confused how to leverage the Error.captureStackTrace()

Can someone explain me on this?

Upvotes: 13

Views: 54007

Answers (4)

Marcos Oliveira
Marcos Oliveira

Reputation: 283

In my case, I had set the wrong path, so the node did not find the right path and what I did was:

  1. Moved my src folder into my server folder.
  2. Executed node again: node src/server.mjs
  3. Done, server up and running.

Upvotes: -1

Kumawat Lalit
Kumawat Lalit

Reputation: 560

So Today I got this error so what you have to do is follow these steps.

first of all, kill your ports by using npx kill-port 8000 see this

  1. check you have installed all the dependencies.(reinstall them)
  2. In my case I have reinstalled all the dependencies.
  3. and if the error still persists, reinstall the node. see this now after following all the steps

Upvotes: -1

Aditya Dixit
Aditya Dixit

Reputation: 43

You can add this to your package.json file.

"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start": "nodemon --experimental-modules --es-module-specifier-resolution=node index.js"
},

Upvotes: -1

eol
eol

Reputation: 24565

One thing you need to understand is that apart from instances of the Error-classs the throw-statement can also throw other types. Consider this for example:

function throwSomeObj() {
    throw {statusCode: 500};
}

try {
  throwSomeObj();
} catch(err) {
  console.log(err);
  console.log(err.stack);
}

The exception that is thrown yields the object you passed to it, i.e. {statusCode: 500}. Now, as you can see this object does not have any stack-trace, since undefined is logged.

However, you can use Error.captureStackTrace to capture the stack-trace where you throw the error. Consider this:

function throwObjWithStacktrace() {
    const someError = {statusCode: 500}
    Error.captureStackTrace(someError)
    throw someError;
}


try {
    throwObjWithStacktrace();
} catch (err) {
    console.log(err);
    console.log(err.stack);
}

As you can see, now err contains the stack property and contains the stack to the function where the error was thrown.

Note that when instantiating a new Error-object the stack will automatically be set on that object.

Upvotes: 9

Related Questions