My knowledge on web technologies (JS, JQ) are limited and I want to start learning them. As a starting point I want to do some file processing. Because it is something I have to do for my work and was planning to do it in Java. What I basically need to do is to go through a list of text files (assembly files) in a folder and search for routines and then list them. This is the first step and is a trivial task in Java.
But I wanted to take this a step further and do it in the browser, so that others in my team also can use it without installing anything (and also to impress them a little bit in the process. since I'm the new guy in the team :-)).
So when I input the folder, the script will go through the files and search and will display results in a web page. Basically first page will be a list of files in the folder, and clicking a file name will take me to another page which displays the routines in that file.
Sorry to bother you with details, but what I actually want to know are:
Is this possible with JS? (to
search for text patterns in a file)
Should I start with JS or JQ? (I
think many would recommend starting
with JS, but since this is a side
project and this is done purely in
my own time, would you suggest start
learning JQ because it's relatively
simpler to learn (from what I have
read) for a beginner?
Or should I just do the processing
in JAva and then interface the
results to a webpage
Any advice is appreciated.
Thank you very much.
Java and JavaScript have nothing to do with each other, jQuery is library written to simplify usage of JavaScript with some handy shortcuts.
I'm afraid JavaScript would not be able to parse text files as its main usage is manipulating content inside browser window and limited by different security policies.
To parse files you have to chose server side language.
maybe you can use java to deal with the file processing, and then send the result to js script , which will show these results to users.
js's ability is limited
For security reasons, JavaScript is sandboxed within the browser, and has basically no access to the local file system. From what you have described, it sounds like your best option is to use Java to process ...whatever...
This function has nothing to do with web browsing. Why is a browser the best tool for the job, anyway?
Related
I am working on an old enterprise solution with these properties:
The solution has a MVC web application
The solution has a WCF service layer
The solution has javascript in the database, in the form of functions in a database column
The web application retrieves said javascript through the service layer and plugs it into certain pages
My team cannot modify the web application, nor the service layer
My team must write javascript by inserting functions into said database columns
This architecture leads to:
A very inefficient development loop
Very poor source control
I'd like to propose a solution for them, how to upgrade this, but here's where I fall a bit short on experience. My suggestion would be:
Migrate the javascript from the database to javascript files
Make some sort of hook in the web application for other teams' javascript files
My questions are:
Has anyone had this kind of problem and how did they solve it?
Is there an effective way to do this kind of javascript migration into files? My idea would be to write a small console program to do the migration
How would they make a hook to import our javascript files? My idea is to make a script bundle with some naming convention, so we can add scripts without them needing to change their code. Are there problems with this approach?
Any kind of input would be invaluable.
Edit:
Additional explanation:
The mechanism maps the javascript function names to a certain DOM elements' event attributes and inlines the code right after the element
The functions are standalone functions, depending only on libraries already in the web application
The functions are grouped by a common form
So I suppose it would be better to group them into files bearing the form names.
If these are just simple, static function definitions being inlined into the web page, then I suppose it might be possible to serialize/aggregate them all into a giant file and run something like prettier on it to make it readable.
That wouldn't be ideal to gain traction in your proposed migration, though. If the code has any volume to it at all, it would be nice to give some structure and order to maintain it.
It's already kind of a huge assumption that this javascript is just pure functions without any complex dependencies on each other, but it's possible that these pieces of Javascript work in isolation already if they are being pulled out of a database. It's hard to know without knowing more context. It seems unlikely that your life will be that easy.
If you managed to extract this monolithic Javascript file, the easiest thing to do would be include it in a script tag for the entire site and be done with it. This could be a bad idea if the file is getting to the ~MB size and slows your initial page load time.
Then again, the point at which you have a bunch of functions in one file, you could probably do a lot there to optimize and reduce duplication of code.
This is still all conjecture because I don't know the mechanism by which your web application imports the javascript once it retrieves it from the database.
This question might have been asked in the past but I cannot seem to find the answer. I would like to navigate between pages without avec to redirect to a brand new xxx.html file. Basically, I want to keep only one html file being the index.html
In order to understand what I mean, here is a small preview of this functionality I want to achieve.
Preview
As you can see, the piece of clothing is not its individual html file. What method is used to achieve this?
What you are seeing is called a Single-Page-Application. There are a lot of frameworks with which you can create a page like this. If you are going for plain HTML/CSS/JavaScript it will be a lot harder to do correctly.
What you're seeing here is a dynamic webpage that is taking advantage of client-side technology to create this effect. To help further explain, let's quickly go over some web development terminology:
Client-Side: Code that is executed on the user's computer (in this case in their web browser).
Server-Side: Code that is executed on a server, then a response of some sort is sent to the client.
With server-side code, the value cannot change unless a new call is made to the server to get a new response. This is because the code isn't actually running on the computer the user is running, it's running on some other computer probably thousands of miles away. However, with client-side code, dynamic changes could be made in real-time because the code is actually running on the user's computer.
When it comes to server-side code, we as developers have a myriad of options. Any language that can send an HTTP response to a web browser could theoretically be used as a server side language. In 2018, that's basically every major language in existence! That being said, some popular options today include Python, Ruby, Java, and Javascript (Node JS).
When it comes to client-side code, however, we're limited by what can run in a user's web browser. In general, modern web browsers only understand Javascript. However, while the language has gotten better over the years, writing code in pure JavaScript can sometimes be cumbersome, so there are libraries that help make writing Javascript easier (such as jQuery) and there are even languages that compile down to Javascript to add new syntax and functionality (such as Typescript and Coffeescript).
If you'd like to start writing dynamic web applications, a good place to start would be to learn the basics of JavaScript. Then, maybe start learning jQuery, or front-end libraries such as Angular or React. Good luck!
You will have to use javascript for this. Either you can load all content at once and just show/hide the content you need, or you could ajax to fetch the content and then render it without page reload.
I have some html files that I need to do automated processing on, basically regex replaces, but also some more complex actions like copying select blocks of text from one file to another.
I want to create a series of scripts that will let me do this processing (it will need to be done more than once on different batches of files). It would be trivial to use Go for this (read the file into memory, regex, save to disk) but I am the only member of the project that's familiar with Go.
Javascript is a tad more ubiquitous, and I do have project members who are familiar with the language, so it's a better fit in that respect. If I'm not around later, someone else could edit the scripts.
Is there a simple way to write some JS scripts to do on-disk text processing? I'm looking for a cross-platform solution (OSX, Windows). Ideally, once the scripts are written, they can be executed by double-clicking an icon--there will be "not computer people" involved at some point.
Also, I'd like to be able to do some kind of alert/message box to inform the user of the success/failure of the script. (This may be a tall order, and is of secondary importance.)
What I've looked at:
Node.js was the first thing that popped into my head, because I know that it has file system access tools, and obviously regex capacity. But I've never used Node before, and based on the tutorials I've read, it seems like overkill for something this simple.
There's a whole slew of "javascript compiling" tools that you can find by googling around. Some are not cross-platform, some seem old or not actively maintained, etc. None of them caught my eye as easy to pick up and just write some JS scripts with.
Any thoughts?
Node.js is a simple solution and with it's framework you can create or later modify your script to your needs. This way you will not be locked down by someone else's code. And it is not that difficult to to use.
Here is a quick tutorial on accesing files using node.js
http://www.sitepoint.com/accessing-the-file-system-in-node-js/
And here is a quick tutorial on using a node module called Cheerio. It allow you to access html files using "jquery like syntax". You don't need to use regex.
http://maxogden.com/scraping-with-node.html
I worked on a project for a client once and it required parsing thru hundreds of html files to check and replace certain image files based on certain criterias. I wasn't familiar with node at the time so I read some tutorials and wrote the script in about an hour.
And as long as Nodejs' path is set, you can run it on the command line.
Some tips:
You need any kind of DOM HTML parser, not only JS nor specifically JS.
You can do that thing with Java with use of jTidy or jSoup libraries (I've used second one few times). It's pretty simple language to learn if you know JS and IDE like Netbeans helps a lot. So can be made quickly with that.
You can use PhantomJS to create some job files and create shell/batch code to run them on some files. You might need to write a generator for job files (like taking a list of files, creating job files for each and running them).
You can use Node.js which isn't much overkill, I'm sure any solution won't be trivial.
You can create an ETL for processing with for example Pentaho ETL (which has JS embedded as one of two scripting languages... but without DOM parser - for that one you would need to use a bit of Java there and some library in way similar to this article).
You can also do that with PHP with Simple HTML DOM Parser - so you can make a service online (or on local server) that takes those html files and throws out processed ones.
First I think you underestimate the complexity. The statement
"It would be trivial to use Go for this (read the file into memory,
regex, save to disk) but I am the only member of the project that's
familiar with Go."
is probably false. Parsing HTML with RegExp is just a bad idea. (Google it and you will see why)
Second, if you can trivially write the code using RegExps in Go, you can just as easily write the same thing in Javascript. They both support RegExp and file operations. If you are unsure about the Javascript/Node.js details, I suggest writing the trivial solution in Go and then translate the thing into Javascript with a colleague.
Since Javascript is a script language, writing command line utilities in Node.js is straight forward.
Some pointers to get you started
RegExp in Javascript
Building command line apps in Node.js
What I am trying to do (no alternative suggestions please, I know more conventional solutions) Easily scrape data from web pages such as images without writing any site-specific code (e.g. to get the biggest image at a particular URL). This is just ONE possibility.
What I'm dreaming of (for other uses too)
I know you can scrape using many APIs that use a DOM model. But surely someone's thought of something higher level? One of the most attractive things about shell script is the data manipulation you can do with basic file I/O with basic commands: Grep plus regular expressions (awk, sed, perl) can instantly put you in touch with goldmines of file-based data. What shell scripts are to files, javascript should be to web pages. But code gets so messy when you address things by tags and attributes. Wouldn't it be wonderful if there was some kind of API like this?
# determine the biggest image by checking images[0].height etc.
$("< http://www.cnn.com/man-has-three-eyes.html").images[0].url
Has such an API ever been attempted? I'm guessing not. If not, what makes this technically unrealistic? If so, what kind of javascript frameworks are the closest thing to offering this?
(If it doesn't, I should file for trademark protection on the brand name "Scrapy Eye" or "ScrAPI" or something!)
I want to add Excel button below the html table, that gives an Excel sheet of the table. I am using C# behind it, but I want it do on client side just using jQuery or Javascript without using PHP or .NET... Not more.
I am searching for hours however I don't find any fix solution. There it said you can use activeX object and CSV however I don't see any running examples.
ActiveX will only run on Internet Explorer so your solution will be limited to that platform.
Without ActiveX or server side scripts there is no way to achieve this due to JavaScript security designs it is not allowed to create files or push in memory files to download streams.
I would not recommend ActiveX or anything that tries to run code outside of the browser on the client system. ActiveX only works on IE not to mention the inherent security risks that brings about.
A possible method would be to use a server side script along with jquery to generate the file and return it without ever leaving the page your on. It looks good and you don't really have to jump through hoops to make it work nor will the user. (if you want an example of the jquery required to do this let me know).
For c# there is alot of tutorials on generating excel files from your data for example here.
The only reason I can think of that you would want to create the file locally is use of resources on your server. C# will be extremly efficient in generating that file not to mention there are a couple things you can do (dependant on the data) to negate any impact it has:
If the data changes are few and far between consider storing the
generated file and directing to that the next time until the data has
been changed.
Limit the data set it returns by way of a search criteria
There are plenty more optimization you could do but you get the idea.