PhantomJS error handling

Question

I'm having a hard time understanding how PhantomJS handles errors.

I have a locally installed Apache server running (xampp), and when I manually visit "http://localhost/" I get the "It Works!" page.

As a test, I wrote a small file (called forceError.js) that purposely causes an unchecked exception:

var page = require('webpage').create(),
    url = 'http://localhost/';

page.onError = function(msg, trace) {
  console.log("page.onError");
  var msgStack = ['ERROR: ' + msg];
  if (trace && trace.length) {
    msgStack.push('TRACE:');
    trace.forEach(function(t) {
      msgStack.push(' -> ' + t.file + ': ' + t.line + (t.function ? ' (in function "' + t.function +'")' : ''));
    });
  }
  console.error(msgStack.join('\n'));
};

phantom.onError = function(msg, trace) {
  console.log("phantom.onError");
  var msgStack = ['PHANTOM ERROR: ' + msg];
  if (trace && trace.length) {
    msgStack.push('TRACE:');
    trace.forEach(function(t) {
      msgStack.push(' -> ' + (t.file || t.sourceURL) + ': ' + t.line + (t.function ? ' (in function ' + t.function +')' : ''));
    });
  }
  console.error(msgStack.join('\n'));
  phantom.exit(1);
};

page.open(url, function (status) {
    console.log("status: " + status);

    // an undefined function
    thisShouldForceAnError();
});

When I run this using:

phantomjs.exe forceError.js

First I get "status: success" and then the process just hangs. I don't see either page.onError or phantom.onError being invoked.

Is there some property or something I need to turn on to get general error handling?

I'm on Windows 7, PhantomJS version 2.0.0, and running this in my "git bash" shell.

Answer 1

Your app hangs because it looks there is a loop when you call console.error within phantom.onError. Check this: Phantomjs v2, consume huge memory+cpu, after throwing exception.