CODEWITHSUNDEEP
javascriptdebuggingnode.js
nevf
nevf

Reputation: 4826

Catch node.js undefined variable

In normal Javascript in the Browser Google Chrome will display an error in the console when you try to use an undefined variable. However in Node.js no error is displayed and I think the function that is using the undefined variable exits.

I've added:

process.on('uncaughtException', function(err) {
    console.log( 'uncaughtException :', err );
});

but this isn't executed.

I've also added try-catch in the calling function and no exception is raised there.

And I'm using: "use strict";

So my question is, is there some way I can get/see an error when an undefined variable is accessed?

Upvotes: 1

Views: 2762

Answers (2)

nevf
nevf

Reputation: 4826

The reason I'm not seeing this exception is other exception handler code is getting in before node. See my replies above re. the MongoDB driver.

Any other suggestions welcome. This is the code that is catching the exception:

          catch (err) {
            var errorObject = {err:"socketHandler", trace:err, bin:self.buffer, parseState:{
              sizeOfMessage:self.sizeOfMessage, 
              bytesRead:self.bytesRead,
              stubBuffer:self.stubBuffer}};
            if(self.logger != null && self.logger.doError) self.logger.error("parseError", errorObject);
            // We got a parse Error fire it off then keep going
            self.emit("parseError", errorObject, self);
          }

Neville

Upvotes: 0

Domenic
Domenic

Reputation: 112827

Node will do this automatically.

// test.js
"use strict";

function badFunction() {
    return iDontExist + 3;
}

badFunction();

Then:

C:\Users\Domenic\Programming>node test.js

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
ReferenceError: iDontExist is not defined
    at badFunction (C:\Users\Domenic\Programming\test.js:4:12)
    at Object.<anonymous> (C:\Users\Domenic\Programming\test.js:7:1)
    at Module._compile (module.js:444:26)
    at Object..js (module.js:462:10)
    at Module.load (module.js:351:31)
    at Function._load (module.js:310:12)
    at Array.0 (module.js:482:10)
    at EventEmitter._tickCallback (node.js:192:40)

Upvotes: 1

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