Tests for any deep inequality.
OK: and are not deeply equal
If the values are deeply equal, an is thrown with a property set equal to the value of the parameter.
If the parameter is undefined, a default error message is assigned.
If the parameter is an instance of an then it will be thrown instead of the
Tests shallow, coercive inequality with the
Tests strict inequality between the and parameters as determined by the
Tests if is truthy.
It is equivalent to
If no arguments are passed in at all will be set to the string:
Be aware that in the the error message will be different to the one thrown in a file!
It will then check that the promise is rejected.
If is a function and it throws an error synchronously, will return a rejected with that error.
If the function does not return a promise, will return a rejected with an error.
In both cases the error handler is skipped.
Besides the async nature to await the completion behaves identically to
If specified, can be a, a validation function, an object where each property will be tested for, or an instance of error where
each property will be tested for including the non-enumerable and properties.
If specified, will be the message provided by the if the block fails to reject.
Note that cannot be a string.
If a string is provided as the second argument, then is assumed to be omitted and the string will be used for instead.
This can lead to easy-to-miss mistakes.
Please read the example in carefully if using a string as the second argument gets considered.
Expects the function to throw an error.
Custom error object / error instance:
Note that only properties on the error object will be tested!
Fails due to the different and properties:
This tests for and
Validate using constructor:
Validate error message using
Using a regular expression runs on the error object, and will therefore also include the error name.
Custom error validation:
Using the same message as the thrown error message is going to result in an error.
The second argument is a string and the input function threw an Error.
The first case will not throw as it does not match for the error message thrown by the input function!
In the next example the message has no benefit over the message from the error and since it is not clear if the user intended to actually match against the error message, Node.js thrown an `ERR_AMBIGUOUS_ARGUMENT` error.
Throws an error:
The string is only used (as message) in case the function does not throw:
If it was intended to match for the error message do this instead:
Does not throw because the error messages match.
Due to the confusing notation, it is recommended not to use a string as the second argument.
How to Contribute in Issues
Asking for General Help
Discussing non-technical topics
Submitting a Bug Report
Triaging a Bug Report
Resolving a Bug Report
For any issue, there are fundamentally three ways an individual can contribute:
By opening the issue for discussion: For instance, if you believe that you have uncovered a bug in Node.js, creating a new issue in the issue tracker is the way to report it.
By helping to triage the issue: This can be done either by providing supporting details (a test case that demonstrates a bug), or providing suggestions on how to address the issue.
By helping to resolve the issue: Typically this is done either in the form of demonstrating that the issue reported is not a problem after all, or more often, by opening a Pull Request that changes some bit of something in in a concrete and reviewable manner.
Because the level of activity in the repository is so high, questions or requests for general help using Node.js should be directed at the Node.js help repository.
Discussion of non-technical topics (such as intellectual property and trademark) should be directed to the repository.
When opening a new issue in the issue tracker, users will be presented with a basic template that should be filled in.
Thank you for reporting an issue.
This issue tracker is for bugs and issues found within Node.js core. If you require more general support please file an issue on our help repo.
Please fill in as much of the template below as you're able.
if known, please specify affected core module name
If possible, please provide code that demonstrates the problem, keeping it as simple and free of external dependencies as you are able.
Enter your issue details below this comment.
If you believe that you have uncovered a bug in Node.js, please fill out this form, following the template to the best of your ability. Do not worry if you cannot answer every detail, just fill in what you can.
The two most important pieces of information we need in order to properly evaluate the report is a description of the behavior you are seeing and a simple test case we can use to recreate the problem on our own. If we cannot recreate the issue, it becomes impossible for us to fix.
In order to rule out the possibility of bugs introduced by userland code, test cases should be limited, as much as possible, to using only Node.js APIs. If the bug occurs only when you're using a specific userland module, there is a very good chance that either (a) the module has a bug or (b) something in Node.js changed that broke the module.
See How to create a Minimal, Complete, and Verifiable example.
Once an issue has been opened, it is not uncommon for there to be discussion around it. Some contributors may have differing opinions about the issue, including whether the behavior being seen is a bug or a feature. This discussion is part of the process and should be kept focused, helpful, and professional.
Short, clipped responses—that provide neither additional context nor supporting detail—are not helpful or professional. To many, such responses are simply annoying and unfriendly.
Contributors are encouraged to help one another make forward progress as much as possible, empowering one another to solve issues collaboratively. If you choose to comment on an issue that you feel either is not a problem that needs to be fixed, or if you encounter information in an issue that you feel is incorrect, explain why you feel that way with additional supporting context, and be willing to be convinced that you may be wrong. By doing so, we can often reach the correct outcome much faster.
In the vast majority of cases, issues are resolved by opening a Pull Request. The process for opening and reviewing a Pull Request is similar to that of opening and triaging issues, but carries with it a necessary review and approval workflow that ensures that the proposed changes meet the minimal quality and functional guidelines of the Node.js project.