python struct.pack equivalent for pure javascript - javascript

Unable find any specific pure javascript lib to implement below python syntax.
below is python syntax.
result = struct.pack('<i', 6).hex()

there are no pure js libraries which are similar to this feature but I have discovered one third party library python-struct which does the exact operations of python's struct have a look.
A sample from the website.
const struct = require('python-struct'); k=struct.pack(">f",49.9);
the out put will be a js buffer object

Related

Is there a way to integrate an expression using Javascript?

I was creating a project that integrates and differentiates expressions by having like a calculator display for teh user to type an expression and it returns an differentiated/integrated expression.
The problem is that I am using the math.js library and the differentiation function math.derivative works but the integration function math.integral doesn't. Any help? I need the calculator to work for only symbolic integration/differentiation
I have tried linking javascript to other languages like python to do the maths and also I have tried different libraries but both didn't work
Can anyone just provide an simple example of integration using javascript that works and I will try to implement it in my code
Update: can anyone explain how to implement the mathjs-simple-integral library into the math.js libary
this is example code of what I tried doing after I installed the library using npm
import { integral } from 'mathjs-simple-integral';
var expression = "x^2";
var result = integral(expression, 'x').toString();
alert(result);

How to decompress an object compressed by zlib in JavaScript?

In JavaScript project, I want to decompress an object compressed by zlib(Zopfli.js) and I'm trying it with pako.min.js.
However, the example at the official site of pako uses require function which does not exist in JavaScript. Maybe Node.js has this but I'm afraid it would take a lot of time and pains to combine this JavaScript project with Node.js, because I know nothing about Node.js.
Is it any way to get through with this, or another way to decompress the object?
Any information would be appreciated.
What I've already tried
I've already tried zlib.js library for decomressing, but the result is catching the error below which I couldn't find any solution:
const compressed = dataCompressedByZlib;
const inflate = new Zlib.Inflate(compressed);
const plain = inflate.decompress();// -> input buffer is broken
You may use pako.js from here for client side javascript and import it as -
<script type="text/javascript" src="pako.js"></script>
inside your html, as mentioned here-
https://stackoverflow.com/a/22675078/7895283

Access/generate java enums in/from javascript

I have a some amount of Java code in my Project (more specificaly GWT)
I have decided to start using react for future features
Now the problem is that i need to access some Java enum in React to perform calls to server from Javascript (or whatever operation)
My questions are
A) Is there a way to access Java public enum values in Js ? If so ...how ?
B) Is there some tool to generate Javascript .js file from these enum and accesss it that way (maybe maven should know this ?)
Any ideas appreciated
If you are using GWT 2.8.0 you can use the newly introduced annotations. There is a very good blog-post about it: here

VB “Financial.Rate” equivalent in Java or Javascript?

There is a built in function from the Microsoft.VisualBasic assembly.
I can use it in VB like this:
APR = (Rate(TotPmts, -Payment, PVal, FVal, PayType, Guess) * 12) * 100
My current project is in Java or Javascript and I need to use this function.
Answers on the web say just add the namespace and assembly and use the same in Java or Javascript
So how can I use use Financial.
Rate in Java (or perhaps even porting the source code to it)?
Thanks for any help.
In a C# project(or other .NET projects), just simply add Microsoft.VisualBasic.dll as a reference into your project, you can use Financial.Rate in your code, don't forget to add the namespace using Microsoft.VisualBasic; It's very easy because all .NET languages (C#/VB/etc) uses the CIL (Common Intermediate Language), so the .dll files compiled from different languages can be shared.
In a Java project, things are quite different. You need to use JNA(Java Native Access). See JNA.

Abstract Syntax Tree generator for javascript, but available in groovy?

I was using the esprima AST generator for javascript and using node.js. It works great!
Now I need to process the resultant json and would really like to use groovy - I have used groovy for this very successfully in the past. I could use two passes (first use node to create the json files and then use a groovy script to process them). However, given the large number of files I will be processing it is preferable to me to use groovy entirely.
Does anyone know if a AST generator for javascript is available in either Java or groovy? Google searches were fruitless for me - way too many hits!
[Afterthought: If node.js is callable from groovy, then I would need a really good set of directions on how that might be made to work!]

Categories

Resources