Looking at Node's documentation, SystemError extends the Error class. However, if you attempt to use SystemError directly, Node will throw a ReferenceError saying that SystemError is undefined.
Clearly, according to the docs, it is possible to encounter an instance of SystemError, but it seems impossible to recreate such an error in the usual way (e.g. throw new SystemError(args)).
I would like to test some code which is designed to interact with the specified SystemError API as detailed in the docs, but I have no idea how to recreate a SystemError. Is this even possible?
I think that node.js doesn't put SystemError available in order to avoid anyone (npm packages) to use it. So a SystemError is really a SystemError and not something else.
If you want to test it, generate the error : Try to read a file that doesn't exist for example.
An other soluce would be to recreate a lookalike error because you know every property of it. But it's a workaround actually.
https://nodejs.org/api/errors.html#errors_class_systemerror
In the Github https://github.com/DefinitelyTyped/DefinitelyTyped I couldn't find any interface declaration of SystemError.
Except custom implementations made by node-fetch, voximplant-websdk and alexa-sdk.
https://github.com/DefinitelyTyped/DefinitelyTyped/search?q=systemError&unscoped_q=systemError
Related
I have a simple pdf file containing an embedded file (test.xml) I'm trying to add a JS to call it once the pdf file is opened (even with notification to user to accept the risk etc). I've read that to perform that, the JS that should be used is this:
this.ExportDataObject({cName:"test.xml", nLaunch:2});
For some reason, it is not working. I checked the debug js console on my Acrobat reader DC (version 2021.001.20145) the the error shown is TypeError: this.ExportDataObject is not a function. I'm not sure why on my "this" object the ExportDataObject is not available... I think it should be available always, shouldn't it? I also tested without the this. and the error is different ReferenceError: ExportDataObject is not defined.
That makes to think to me that this.ExportDataObject is existing but is not a function as the original error said... but, if is not a function, what is? a typeof is showing "undefined". Not sure how to make this work. Not sure if next steps should more JS debugging or if the problem is related to something on pdfs or Acrobat. Any help? thanks.
Javascript function names are case-sensitive and as documented by Adobe (p. 151), the correct spelling is exportDataObject() without the leading capitalization.
I believe you misspelled ExportDataObject()
It should be exportDataObject()
Using Javascript you should be careful as it is easy to mess up spelling as JS will interpret that in different ways.
As like most of the languages, js is also case sensitive.
But ReferenceError: ExportDataObject is not defined, ReferenceError always states that the object is not defined at all, and could'nt be found among the class methods.
so you need to make sure the function with the exact exportDataObject name is present and use them accordingly.
I've got a web scraper-ish set of functions that I'm writing in Swift, and I'm using the JavaScriptCore library to... well, execute some JavaScript. I've scraped a file from the web, but it only has a couple of functions that I'm interested in. However, parts of the file contain things like window or window.currentScript, or new window.WeakMap... these things are unfortunately not defined in JavaScriptCore.
This is one of the errors that I'm getting, for example:
TypeError: undefined is not an object (evaluating 'window.document.currentScript.src.indexOf')
Something I'm attempting to do in the meantime is monkeypatch all of the erroring things, like this:
window={};window.document.currentScript.src={};window.document.currentScript.src.indexOf={}
And prepending this to the JS. However, there must be a better way... right?
What I ended up doing was disregarding these references to window altogether—the functions I needed from the JS file didn't ever reference window or its properties. I did some regex magic (magix?) to extract the definitions of the functions I wanted, and made a new string for just those functions. Then, I gave that string to JSContext.evaluateScript. I hope this helps someone!
I am new to GWT and trying to create a small application. I am currently assembling a small framework for the app, a generic layout handler, etc. This may not be the last problem I will bump into, but I just cannot find any solution to this on google.
So I have a class type, which return me Composites. Also, I have another one, which stores these kind of classes in Stack (I also tried Vector, I thought maybe GWT has issues with it). It didn't matter. If I call the .clear method on the Stack, I have the aforementioned error in the inspection menu of Chrome:
Uncaught TypeError: Cannot read property 'clear_31_g$' of undefined
Like if GWT does not know, how to convert this method to javascript or what? Do you know what is the problem here?
eclipse neon, Java 7 setting on Java SDK 1.8 (maybe this?), GWT 2.7.0 and App Engine 1.9.34
Thanks!
edit1: I also found the page, which contains the emulated JRE classes' list (http://www.gwtproject.org/doc/latest/RefJreEmulation.html) with all supported methods. Now I see, that clear is not on that list for Stack, but empty does and that gives me the same error. :-/
This error simply means that you try to call the clear() method on a null object (the object is undefined).
The error message itself is not as clear as it could be. First, it's not always about reading a property but also about calling a method. Second, remember that you run a compiled to javascript code and the property (or method) name may differ from the original one - it has something like _31_g$ added in the runtime.
I might be approaching this completely incorrectly, so any advice is appreciated. I'm currently trying to dig in deep to Typescript, and have decided to simultaneously use Sql.js (the JS version of SQLite) at the same time...
My first instinct to use Sql.js was to search for a .d.ts set of bindings around Sql.js so that I could easily start using it with TS. I've come up with no bindings so far (I don't think one exists yet), but figured I could just start "define"-ing in the stuff that I need from the library...
Starting with one of the simple examples from the "sql.js" docs, you have something like this:
var sql = window.SQL;
var db = new sql.Database();
Moving to the typescript side, I wanted to let TS know that after the sql.js library is included, the window object now has a property called SQL, which is essentially the hook to the rest of the library. I figured I needed to do this because, of course, when I type "window." (window-dot) in Visual Studio in my TS file, the Intellisense presented doesn't know about the SQL property now hanging off of "window". So... I dug around Stack, and concluded that I could solve this with a "declare" which I basically see as a way to tell TS just enough about the libraries that I don't have binding files for (.d.ts files).
However, in doing this, I can't seem to construct the syntax for such a declaration. I've tried:
declare var window.SQL : any;
declare var window.SQL;
declare var SQL = window.SQL;
declare window.SQL;
None of these work, of course.
So, the question is, how can I let TS know about new properties introduced by JS libraries on standard objects like "window", and the follow up question is, of course, is this even the right way to be approaching this?
Thanks for any insight.
Now that we have type definitions for SQL.js, and as of Typescript 2.0, the ability to install them easily, you can just do this:
npm install #types/sql.js
Then, that typings file will automatically be picked up by the compiler, and it will know that there is a SQL object. Here is the full definition:
https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/sql.js/sql.js.d.ts
window is declared to be of type interface Window (in lib.d.ts). So you need to add to that if you want to use window.SQL :
interface Window{
SQL:any;
}
var sql = window.SQL;
var db = new sql.Database();
Recommend:
Personally I would recommend not using it off of window and just do
declare var SQL:any;
var db = new SQL.Database();
By default the variable access in the browser is on window.
OK, I think I've figured it out, although I'm still not sure if this is the preferred method.
In inspecting lib.d.ts, which is pretty much the heart of the sun as far as declarations go, I found the declaration of the interface for Window more than once. That led me to the conclusion that TS interface declarations (and likely other declarations) can essentially be "partials". It appears that the definition of any interface can be extended by simply adding extra items in a brand new declaration...
So, currently, my angry red squiggly line under "window.SQL" has gone away by simply adding the following:
interface Window {
SQL: any;
}
This seems to work because in lib.d.ts, the "window" variable is defined as a "Window" like this:
declare var window: Window;
... on line 9867 of the file in case others are looking for it. So, the net effect seems to be, I extended the definition of "Window" based on knowing that sql.js would make a new property called "SQL" on it.
HTH, in case anyone else is spelunking the same concepts.
I use TypeScript to code my javascript file with Object Oriented Programing.
I want to use the node module https://npmjs.org/package/typescript-require to require my .ts files from other files.
I want to share my files in both server and client side. (Browser) And that's very important. Note that the folder /shared/ doesn't mean shared between client and server but between Game server and Web server. I use pomelo.js as framework, that's why.
For the moment I'm not using (successfully) the typescript-require library.
I do like that:
shared/lib/message.js
var Message = require('./../classes/Message');
module.exports = {
getNewInstance: function(message, data, status){
console.log(requireTs);// Global typescript-require instance
console.log(Message);
return new Message(message, data, status);
}
};
This file need the Message.js to create new instances.
shared/classes/Message.ts
class Message{
// Big stuff
}
try{
module.exports = Message;
}catch(e){}
At the end of the fil I add this try/catch to add the class to the module.exports if it exists. (It works, but it's not really a good way to do it, I would like to do better)
If I load the file from the browser, the module.export won't exists.
So, what I did above is working. Now if I try to use the typescript-require module, I'll change some things:
shared/lib/message.js
var Message = requireTs('./../classes/Message.ts');
I use requireTs instead of require, it's a global var. I precise I'm using .ts file.
shared/classes/Message.ts
export class Message{
// Big stuff
}
// remove the compatibility script at the end
Now, if I try like this and if I take a look to the console server, I get requireTs is object and Message is undefined in shared/lib/message.js.
I get the same if I don't use the export keyword in Message.ts. Even if I use my little script at the end I get always an error.
But there is more, I have another class name ValidatorMessage.ts which extends Message.ts, it's not working if I use the export keyword...
Did I did something wrong? I tried several other things but nothing is working, looks like the typescript-require is not able to require .ts files.
Thank you for your help.
Looking at the typescript-require library, I see it hasn't been updated for 9 months. As it includes the lib.d.ts typing central to TypeScript (and the node.d.ts typing), and as these have progressed greatly in the past 9 months (along with needed changes due to language updates), it's probably not compatible with the latest TypeScript releases (just my assumption, I may be wrong).
Sharing modules between Node and the browser is not easy with TypeScript, as they both use very different module systems (CommonJS in Node, and typically something like RequireJS in the browser). TypeScript emits code for one or the other, depending on the --module switch given. (Note: There is a Universal Module Definition (UMD) pattern some folks use, but TypeScript doesn't support this directly).
What goals exactly are you trying to achieve, and I may be able to offer some guidance.
I am doing the same and keep having issues whichever way I try to do things... The main problems for me are:
I write my typescript as namespaces and components, so there is no export module with multiple file compilation you have to do a hack to add some _exporter.ts at the end to add the export for your library-output.js to be importable as a module, this would require something like:
module.exports.MyRootNamespace = MyRootNamespace
If you do the above it works, however then you get the issue of when you need to reference classes from other modules (such as MyRootNamespace1.SomeClass being referenced by MyRootNamespace2.SomeOtherClass) you can reference it but then it will compile it into your library-output2.js file so you end up having duplicates of classes if you are trying to re-use typescript across multiple compiled targets (like how you would have 1 solution in VS and multiple projects which have their own dll outputs)
Assuming you are not happy with hacking the exports and/or duplicating your references then you can just import them into the global scope, which is a hack but works... however then when you decide you want to test your code (using whatever nodejs testing framework) you will need to mock out certain things, and as the dependencies for your components may not be included via a require() call (and your module may depend upon node_modules which are not really usable with global scope hacking) and this then makes it difficult to satisfy dependencies and mock certain ones, its like an all or nothing sort of approach.
Finally you can try to mitigate all these problems by using a typescript framework such as appex which allows you to run your typescript directly rather than the compile into js first, and while it seems very good up front it is VERY hard to debug compilation errors, this is currently my preferred way but I have an issue where my typescript compiles fine via tsc, but just blows up with a max stack size exception on appex, and I am at the mercy of the project maintainer to fix this (I was not able to find the underlying issue). There are also not many of these sort of projects out there however they make the issue of compiling at module level/file level etc a moot point.
Ultimately I have had nothing but problems trying to wrestle with Typescript to get it to work in a way which is maintainable and testable. I also am trying to re-use some of the typescript components on the clientside however if you go down the npm hack route to get your modules included you then have to make sure your client side uses a require compatible resource/package loader. As much as I would love to just use typescript on my client and my server projects, it just does not seem to want to work in a nice way.
Solution here:
Inheritance TypeScript with exported class and modules
Finally I don't use require-typescript but typescript.api instead, it works well. (You have to load lib.d.ts if you use it, else you'll get some errors on the console.
I don't have a solution to have the script on the browser yet. (Because of export keyword I have some errors client side) I think add a exports global var to avoid errors like this.
Thank you for your help Bill.