I don't want to use services like nodetime. I have small middleware nodejs application. And now I my application use cpu in strange way http://s27.postimg.org/fgzmmh85f/cpu.png So I need simple tools to profile my code. I tried to use node --prof app.js but Chrome Dev Tool doen't open generated log-file.
Please advise tool to find out bottlenecks. Also I can't understand how v8 garbidge collector works.
I'm not node expert, but I've been trying to profile some JS code for some time now. This is what I can tell you:
There are two ways to profile, but both provide the same data. The first one is running your code with node --, which will generate an isolate*.log file. You give this file to node --prof-process and this will give you smoe output that, if you're kinda lucky, you can understand and act upon.
The second one is more or less like this:
var profiler = require('v8-profiler');
profiler.startProfiling('carto');
[your code here]
var profile = profiler.stopProfiling('carto');
profile.export(function(error, result) {
fs.writeFileSync('carto.cpuprofile', result);
profile.delete();
})
This will generate a .cpuprofile that you can load in chromium's JS Profiler. This can be found in the Developer Tools, and you will have probably to enable the Javascript Profiler in the More Tools menu. This will give you three different ways to see in which functions you're spending time.
Related
Following my first question, I realized that the reason I couldn't get anything to work was that I was trying to use the require() method in the browser. In learning that this is not how Node works, I was confused. I understand now that Node is only a run-time environment that allows the use of JavaScript within the console. However, I'm still left with the question of how to achieve the functions of Node within the browser. (i.e. creating a button in the browser that creates a file using Node.) I've installed Browserify but I cannot find a good tutorial on how to use it. I'm very new to Computer Science so please forgive me for the redundant questions. Thanks a lot.
Things do change. Apparently it will be possible to use node.js in the browser soon. You might be interested in this: Run Node.js in the browser
Node as you made the point is server-side runtime environment for js and the browser is client-side. Node.js has many useful built-in functionalities and they are not accessible in browser.
I recommend you to take a look how backend and frontend differs and how do they communicate with themselves. Then I think you will understand how to achieve creating a file by clicking a button in the browser.
Sorry I don't know anything about browserify but it would be better to learn node in cli.
I have been using react for about a year now and i recently wanted to delve into react-beautiful-dnd. I've built plugins for vanilla js and jQuery in the past , but i am not to sure about how to go about building a react.js plugin or even debug it. i am more interested in debugging this plugin and seeing how it works more then anything , so how exactly do i go about doing it ?
Typically with a JS plugin, its mostly one file , so a console.log inside each function would give you a clear enough understanding of why and when a certain function is triggered , how would you go about doing the same with a react.js plugin ?
There are multiple ways to debug.
node debug app.js
node-inspector
console
util
Well, I use a lot of well place console.log, console.dir and util.inspect statements throughout my code and follow the logic that way.
react-beautiful-dnd
Unfortunately there is not much documentation and do-how thing for given topic. But here is what I found helpful. you can follow this link for Quick start guide: https://github.com/atlassian/react-beautiful-dnd/issues/363
The codesandbox examples from the docs:
https://github.com/atlassian/react-beautiful-dnd#basic-usage-examples
Sample Project: https://github.com/jacobwicks/rbdnd-2-list-example
All Examples
Basic usage examples
We have created some basic examples on codesandbox for you to play with directly:
Simple vertical list
Simple horizontal list
Simple DnD between two lists
To Debug any Library:
Here's how you can debug that library. This is the most basic method.
Install it.
Check what you are using and what you need to debug.
Find that method in the node_modules.
Check if that method has any declaration in the code.
If yes put some console logs and see if they get printed on console.
Then check console for your logs.
Carry on the process of console logs until you get what you are looking for.
You have to find library's function you want to debug in node_module and console.log from there. You may need to console.log the parsed file usually found in node_module/plugin/lib or node_module/plugin/dist rather then the .jsx file in node_module/plugin/src.
How do I debug Node.js applications?.
This has quite a few answers on how you can go about debugging your react application.
I've just started my IT degree and I'm a beginner to the use of APIs (and forums like this) so I am truly sorry if my question is to vaguely explained or if it is just plain stupid :), on top of that I'm not a native English speaker :P. Okay, so I'm trying to use Google trends' api which I installed in my server with putty by using sudo npm install google-trends-api. (it can be found here https://www.npmjs.com/package/google-trends-api#installation) As I undestand it, this is a server side api so the scripts that I write with the methods provided for this api will not run on an explorer as normal js files do. There is an example that makes use of the API that I found on the page which is as follows
var googleTrends = requite('google-trends-api');
googleTrends.hotTrends('US')
.then(function(results){
console.log(results);
})
.catch(function(err){
console.log(err);
});
this outputs a list of 20 items on the console when I use it on node.
I would like to know if there is a way to assign those results to a variable and then use that variable in a normal javascript script inside a html file. I do not know anything about node.js and the like, and I would like to actually do some research instead of asking here but I was going to use a different approach to acquire such information but now I've had to change my plans and do not have enough time and given I consider this is a fairly easy problem to resolve (maybe?) I would really appreciate it if someone could walk me through the basics of each step. THanks :) and have a nice day.
Your question is quite broad. Node.js is Chrome's V8 engine bundled with some libraries to do I/O and networking. This enables us to JavaScript outside of the browser and to create backend services or servers in general (in your case). I hope that you are aware of this difference :)
The first thing that you have to do, is to have a look at express.js and to create a simple server. It will not be more than 20 lines of code. Then you have to enrich this with more stuff like a template engine (handlebars.js, jade etc). You have to enable the server to serve static files that will be finally your js, css and image files. Creating this simple server you will be able to serve simple html page in the first place. On top of that you should have the client side javascript that you have to write and now you can use the module above. Unfortunately, you are not able to use this module directly on a javascript file that you will write. To be able to use this module you have to transcompile this thing into javascript that browser understand*. Remember that browser does not understand the require statement and some old browsers possibly will have issues with the promises that this module is using. These are the things that should be compiled. You have to use a tool like browserify for this and the compiled file that this will extract it must be included in the scripts of your html page.
Maybe there are quite a lot of concepts that you are not aware of or you don't understand them but spend a bit of time to understand them.
P.S.: I' ve replied under the assumption that google-trends-api module does not use things that are specific to node.js like the file-system for example.
This question is pretty short and self explanatory. I'm wondering how I can run my Chrome extension in NW.js.
I know you can run an app in NW.js and I think you can run extensions as well?
I can't find much on the topic. Back in 2013 the way to do it seemed to be:
nw [path to manifest.json] --load-extension
Any ideas are appreciated!
Yes you can.
First off, download the extension you want. For this example I'll be using this debugging tool, which adds an additional tab in the dev tools window.
Inside your NW.js package.json file, ensure you have an entry called chromium-args.
Ensure its value contains --enable-extensions --load-extension=relative_path_to_extension_manifest.
My package.json looks like this:
After restarting the application, the extension shows up as expected:
Something I'll add is that the full Chrome API might not be available to you. I couldn't find info about what NW.js supports, but Electron definitely does not support the entire API, so this might have similar restrictions.
I also noticed you mention in the comments that you need to assign a hotkey of sorts. I'd need to know what you were trying to do, but essentially you have the option of either using a browser mechanism such as addEventListener('keydown', myHandler) or using the NW.js API depending on your exact needs.
I have a difficult question that needs some answering, i have seen some projects where
the application runs a socket in a browser that has a console like format that the user can run for their node.js module...
If the actually calling a function or script is impossible from the web side,
i think it would be nifty to just see the console logs in the window.
If any advice could be shared, that would be amazing!
Thanks :)
Yes, there are several projects that do this. Weinre is very commonly used. You can look at its source code to see how it does it.
If I were to build it from scratch, I would utilize Socket.IO. Send the command, return the result.