Develop Reference

loadJSON not Defined - Chrome Extension Error

I'm incredibly new to HTML/Javascript/API's and im trying to make my first chrome extension using coinmarketcaps' public API.
API: https://api.coinmarketcap.com/v2/ticker/?limit=12&sort=rank&convert=ETH
My Code:
console.log("Running");
function setup() {
loadJSON('https://api.coinmarketcap.com/v2/ticker/?
limit=12&sort=rank&convert=ETH', gotData, 'jsonp');
}
setup();
function gotData(data){
console.log(data);
list = data;
}
gotData();
Essentially what I want to do is load in the data and then print the data to my console to make sure that it is in fact loaded. The error that I'm getting when i check the background.js console after uploading the extension is 'loadJSON is not defined'
I don't know if im missing a package or am unable to use such a command but after looking online for a while I can't seem to figure it out. Another thought that I had was maybe it can't be used in a background.js file. Also, I am using Atom software for this project. Let me know if you need any more information, any help is appreciated.

How to write file in Google Chrome App without prompting?

I am fumbling around with the free Chrome Dev Editor on my Chromebook. I am trying to use the fileSystem to read and write .txt files. It is all very wrapped up, not at all like in C. I can no more tell if I am even allowed to do something, let alone where the proper place is to find out how.
I think the files I can see using the Files thingy are in the sandbox that I am allowed to play in (meaning, folders that are accessible by the app?) The root is called Downloads. Sure enough, if I use all the dot calls and callback arguments for the read, as in the examples at developer.chrome.com/apps/filesystem, it works. But I have to have a prompt
every time for both reads and writes.
A little more Googling came up with this trick: (I think it was here in stackoverflow, in fact) a chrome.runtime call, getPackagedDirectoryEntry, that seems to give me a handle to the folder of my app. Great! That's all I need to not have to go through the prompting. For the readfile, anyway.
But then trying to apply the same trick to the writefile did not work. In fact, it did nothing discernible. No errors, no complaints. Nothing. Even though the write file with prompting works fine (so presumably I have the permissions and Blob construction right.) What to do?
Here is my code:
function test(){
// Samsung 303C Chromebook - Chrome Dev Editor - /Downloads/Daily/main.js
// prompted write
chrome.fileSystem.chooseEntry({type:'saveFile'},function(a){
a.createWriter(function(b){
b.write(new Blob(["Programming fun"],{type:'text/plain'}));
},function(e){trace.innerText = 'error is ' + e;});
});
// unprompted read
chrome.runtime.getPackageDirectoryEntry(function(a){
a.getFile('text.txt',{},function(b){
b.file(function(c){
var d = new FileReader();
d.onloadend = function(){trace.innerText = this.result;};
d.readAsText(c);
});
});
});
// unprompted write - why not?
chrome.runtime.getPackageDirectoryEntry(function(a){
a.getFile('new.txt',{create:true},function(b){
b.createWriter(function(c){
c.write(new Blob(["Miss Manners fan"],{type:'text/plain'}));
},function(e){trace.innerText = 'error is ' + e;});
});
});
}

To be fair, Filesystem API is a big mess of callbacks and it's not unreasonable to get drowned in it.
It's not currently documented, but chrome.runtime.getPackageDirectoryEntry returns a read-only DirectoryEntry, and there is no way to make it writable (it's specifically blacklisted).
You probably don't see an error, because it fails at the getFile stage, for which you don't have an error handler.
Unfortunately, for a Chrome App the only option to write out to a real filesystem is to prompt the user. However, you can retain the entry and ask only once.
If you don't need to write out to the real filesystem but need only internal storage, HTML Filesystem API can help you (yes, it's marked as abandoned, but Chrome maintains it since chrome.fileSystem is built on it).
Extensions additionally have access to chrome.downloads API that enables writing to (but not reading) the Downloads folder.
P.S. What you see in Files app is your "real" local filesystem in ChromeOS + mounted cloud filesystems (e.g. Google Drive)

You can use the basic web Filesystem API. First, add the "unlimitedStorage" permission. Then, copy the packaged files to the sandboxed filesystem, like this:
chrome.runtime.getPackageDirectoryEntry(function(package) {
package.getMetadata(function(metadata) {
webkitRequestFileSystem(PERSISTENT, metadata.size, function(filesystem) {
package.copyTo(filesystem.root)
})
})
})

Write a variable to a file in Javascript

This may be a copy.. but I'm not getting the thing I want from the answers I saw..
I just want to save a particular variable into a local file using Javascript. I know how to read a file.
I wrote this code..
<script>
var fs = require('fs');
fs.writeFile('http://localhost/online/hello.txt', 'Hello Node', function (err) {
if (err) throw err;
else
{
console.log('It\'s saved!');
}
});
</script>
What is the error here.. or is there a simple and straight-forward way of doing it..??

It seems you're trying to call node-js code from the browser. Although javascript can run in both the browser and on the server (node-js), those are separate systems.
Another thing you can do is google "HTML save file example" and see how this is typically implemented - by opening a save dialog for the user, getting his/her permission, etc. (otherwise any website could just write any file to your computer...).

You are writing NodeJS code for client side application. You must understand the difference between javascript on browser and javascript on NodeJS platform.
Javascript is a language just like C, Java and Python
V8 is a javascript engine to run the javascript application. It is something similar to JRE for Java.
Browser(Only Chrome) uses V8 engine for running javascript application. Other browsers use different javascript engine. Five years ago, there was only one possibility that javascript can only work on browser. You cannot use javascript for application programming like C and Java
NodeJS is a platform which uses V8 to enables developer to write javascript application just like C, Java program. NodeJS also has some inbuilt library for accessing file system,
networks, and much more utilities. One of the internal library in NodeJS is fs. It only works on NodeJS application, not on browser application.

This can be done pretty simply using jrpc-oo. jrpc-oo links the browser and nodejs using the JRPC2 protocol. jrpc-oo abstracts classes over JRPC so that either side (nodejs or the browser) can call eachother.
I have setup an example repo to do exactly this here. Use the writeToFile baranch. I will break out the important parts here.
First in nodejs, we write a class with a method to write input arguments to file. The method looks like so (from the file TestClass.js) :
const fs = require('fs');
class TestClass {
writeToFile(arg){
fs.writeFileSync('/tmp/browser.json',JSON.stringify(arg));
}
}
In the browser we inherit from the jrpc-oo class JRPCClient and call the server class TestClass and method writeToFile like so (from the file src/LitJRPC.js) :
import {JRPCClient} from '#flatmax/jrpc-oo/jrpc-client.js';
export class LitJRPC extends JRPCClient {
writeObjToFile(){
// create the argument we want to save to file
let dat={name:'var',value:10};
// Ask the server to execute TestClass.writeToFile with args dat
this.server['TestClass.writeToFile'](dat);
}
}
Finally we run the nodejs app and the web-dev-server and we look at the browser console and nodejs console to see what happened. You will see the browser variable dat saved to the file /tmp/browser.json
As we are using a secure websocket for jrpc, you will need to generate the certificate and clear the certificate with the browser before the app will work. If you don't want to worry about security then don't use secure websockets. Read the readme in the reference repo for more information on setup and usage.

Can I/how can I translate a Selenium webdriver test script from node.js over to phantomjs - ghostdriver?

I recently began working with Selenium and to make life easier to start I was using node to run my scripts so that I could visually monitor the tests. My challenge now is to convert it so that it can be run as a headless test. Unfortunately, most of the resources that I have come across only address using phantomjs and ghostdriver with Java or Python. My boss wants me to run the test through phantomjs without Java or Python. Eventually these tests will be run remotely through a Linux VM on a server without a GUI. Currently I am testing using Mac OS X 10.8 and still have many bridges to cross in order to get to my goal.
My most important question firstly, is it possible to run a script from phantomjs through a port without the use of Java or Python? I have spent hours poring through as many resources as I could come across and I've come up with no solution.
If so, how can I properly initialize the test to run headless? Here is how I scripted the start of my functioning test. I want to properly switch the capabilities from firefox to phantomjs and be able to run it headless using the appropriate port. The rest of the test navigates to a specific site, logs in through a widget, then does further navigation to the area which I will build further tests on which to manipulate after I get this working.
var webdriver = require('selenium-webdriver'),
SeleniumServer = require('selenium-webdriver/remote').SeleniumServer;
var server = new SeleniumServer("Path/selenium-server-standalone-2.39.0.jar", {
port: 8910
});
server.start();
var driver = new webdriver.Builder().
usingServer(server.address()).
withCapabilities(webdriver.Capabilities.firefox()).
build();
The test works perfectly, but I am new to this so there might be something foolish that I am overlooking. Please let me know what adjustments to make so that it will run headless through phantom. When I attempt to use node to run the script after switching capabilities to phantomjs it produces
"/Selenium/node_modules/selenium-webdriver/phantomjs.js:22
LogLevel = webdriver.logging.LevelName,
^
TypeError: Cannot read property 'LevelName' of undefined
at Object.<anonymous> (/Selenium/node_modules/selenium-webdriver/phantomjs.js:22:33)
That's a read only file that I can't adjust, any attempts that I made to define "LogLevel" or "LevelName" to the appropriate corresponding value (DEBUG, etc.) were fruitless.
And if I run it through phantomjs itself I get -
"Error: Cannot find module 'path'
phantomjs://bootstrap.js:289
phantomjs://bootstrap.js:254 in require"
(It also lists module 'http') -- (and various undefined function errors)
I feel that with that instance I didn't properly organize where the files for Selenium, phantomjs, and ghostdriver should go in order to play nice. I also removed the server setup portion and instead ran this first, then the script separately.
phantomjs --webdriver=8910
But it yielded the same result. All of my research to fix these issues turned up instructions for Java and Python but not Javascript by itself. Rather than chase through many rabbit holes I figured it wise to consult better minds.
If you know better than I do and that it is fruitless to attempt this without Java or Python, please let me know. If you know where the issue lies within my script and could propose a fix please let me know. I hope that I have properly described the nature of my issue and if you need more information I will do my best to provide it to you.
This is my second week working with Javascript so if you believe I am making a noob error you very well may be correct. Please, keep in mind that the script works through node with selenium webdriver.
Many thanks for your time!!!
~Isaac

This was a bit tricky but here is the solution I've pieced together:
var webdriver = require('selenium-webdriver'),
SeleniumServer = require('selenium-webdriver/remote').SeleniumServer,
server = new SeleniumServer('/path/to/selenium/selenium-server-standalone-2.41.0.jar', {
port: 4444
}),
capabilities = webdriver.Capabilities.phantomjs();
capabilities.set('phantomjs.binary.path', 'path/to/phantom/bin/phantomjs');
var promise = server.start().then(function() {
var client = new webdriver.Builder().
usingServer(server.address()).withCapabilities(
capabilities
).build();
return {
'client': client,
'server': server
};
}, function(err) {
console.log('error starting server', err);
});
You can then use the promise with selenium's mocha-compatible test framework to hold the test till the server has started.
I found the documentation really helpful once i figured out the navigation is on the far right of the page. Here's the URL: http://selenium.googlecode.com/git/docs/api/javascript/module_selenium-webdriver.html
Then you'll be stuck where I am. Getting selenium-webdriver to quiet down.

Log JavaScript console into a log file with Firefox

We have a web application which runs in a kiosk mode Firefox, using the RKiosk extension to achieve this. We suspect that we have a very rare error in the system which yields in a JavaScript error. However because we can't access the JavaScript console we can't examine the log.
I'm searching for an option to make Firefox log all JavaScript console messages into a file regardless of the tab and page opened. I can't seem to find any extension for this. I'm already using log4javascript which sends errors back to the server, but it seems that our application crashes in a way that it skips the logging altogether.

Writing to a file sounds like a tedious task to me. It requires privileges that browser code doesn't normally have and you'd have to negotiate with an add-on you'd have to write in order to access file I/O.
From what I understand your issue is
I'd like to make Firefox log all errors
There are several approaches we can do to tackle this
First approach - log everything to localStorage too:
Now, rather than writing to an actual file, you can write to localStorage or IndexedDB instead.
localStorage["myApplog"] = localStorage["myApplog"] || "";
var oldLog = console.log;
console.log = function(){
oldLog.apply(console,arguments); // use the old console log
var message = "\n "+(new Date).toISOString() + " :: "+
Array.prototype.join.call(arguments," , "); // the arguments
localStorage["myApplog"] += message;
}
This is rather dirty and rather slow, but it should get the job done and you can access the log later in local storage. LocalStorage has a ~5MB limit if I recall correctly which I think is enough if you don't go crazy with logging. You can also run it selectively.
Second approach - log only errors
This is similar to what Pumbaa80 suggested. You can simply override window.onerror and only log errors.
// put an empty string in loggedWinErrors first
var oldError = window.onerror || function(){};
window.onerror = function(err,url,lineNumber){
oldError.call(this,err,url,lineNumber);
var err ="\n Error: (file: " + url+", error: "+err+", lineNumber: "+lineNumber+")");
localStorage["loggedWinErrors"] += err;
}
Third and drastic approach - use a VM.
This is the most powerful version, but it provides the most problematic user experience. You run the kiosk in a virtual machine, you detect an uncaught exception - when you do you freeze the machine and save its state, and run a backup VM instead. I've only had to do this when tackling the most fearsome errors and it's not pretty. Unless you really want the whole captured state - don't do this.
Really, do the extension before this - this is tedious but it gets very solid results.
In conclusion, I think the first approach or even just the second one are more than enough for what you need. localStorage is an abstracted storage that web pages get for saving state without security issues. If that's not big enough we can talk about an IndexedDB solution.
It all really depends on the use case you have.

You can use XULRunner...a Mozilla runtime environment for XUL applications. It uses Gecko like Firefox and:
You can access the file system or using the SQLite database to store logs.
You can render your kiosk in fullscreen mode without using extensions.

Have you tried jserrorcollector? We are using it and it works fine (only in Firefox). It's only for Java.
// Initialize
FirefoxProfile ffProfile = null;
ffProfile = new FirefoxProfile();
JavaScriptError.addExtension(ffProfile);
// Get the errors
List<JavaScriptError> jsErrors = JavaScriptError.readErrors(webDriver);
More information: https://github.com/mguillem/JSErrorCollector

Have you considered remote logging?
I commonly assign window.onerror to do send a request to a webserver storing the details of the error remotely. You could do the same with console.log if you preferred.

Try the following console export. It is a plugin for Firebug of Firefox. It's quite handy.
http://www.softwareishard.com/blog/consoleexport/

If you are able/willing to switch from Firefox to Chrome or Opera you would be able to use the Sandboxed Filesystem API to write a local file. See:
http://www.html5rocks.com/en/tutorials/file/filesystem/
http://caniuse.com/filesystem
Start in kiosk mode using chrome.exe --kiosk <url>
You would then want to disable Alt-F4 and Ctrl-Alt-Del which on Windows can be done with several third-party tools like Auto Hotkey (Disable Ctrl-Alt-Del Script).

You could use a remote logging script like Qbaka. It catches every JS error and sends it to the Qbaka server. There you can login and see all JS errors. Qbaka stores the exact error message, the script, line number, stack trace and the used browser for each error message.