const AsyncFunction = Object.getPrototypeOf(async function () {}).constructor
const fn = new AsyncFunction('a','await blah')
So I'm trying to create a function using new AsyncFunction
This is working perfectly on the server. But when I do tsnode script.ts, I got
SyntaxError: await is only valid in async functions and the top level bodies of modules
for the exact line.
Somehow tsnode is creating a normal function instead of an async one. Is there any trick around this?
In my case, the exact fn defintion in string is:
`try{ ${js}\n return await ${fnName}(${args}) \n}catch(err){console.log('err ',err)}`
So if I get rid of await, it works ie
`try{ ${js}\n return ${fnName}(${args}) \n}catch(err){console.log('err ',err)}`
Still doesn't resolve the main tsnode async-fn creation problem, but this is a trick that unstucks me
Related
I a using the library puppeteer however I would only like to instantiate one browser. So I'm using a top level function to create the browser and passing it as a parameter to helper functions like so:
import * as puppeteer from 'puppeteer';
export async function scrape() {
const browser = await puppeteer
.launch({
//product:'chrome',
//executablePath: '/usr/bin/chromium-browser,
args: ['--no-sandbox', '--disable-setuid-sandbox'],
})
.catch(() => {});
scrapeVmb(browser)
scrapeChase(browser)
}
The problem becomes that I lose the intelisense inside the helper functions for the pupeteer library, This problem could be solved by setting the type of the browser parameter, however I do not know where to find the type of browser.
TLDR
How can I get the browser parameter to inherit the browser type inside the "scrapeVmb" and "scrapeChase" functions.
After fiddling around with it some more (I don't understand HOW this works so if someone knows it might be worthy of an answer) you can do:
type browserType = puppeteer.Browser
That will give you the browser interface which you can then use like so:
function scrapeEtc(browser:browserType) {
//...
{
I'm building an Electron app that needs to use Web-Assembly (WASM), however I'm hitting an issue with Fetch throwing a TypeError: Only absolute URLs are supported when importing my WASM file.
Also, perhaps this raises the broader question as to whether the Electron main process or the renderer process should be used to run the WASM ? It does seem to work in the render process.
Here's the complete error:
TypeError: Only absolute URLs are supported
at parseURL (/Users/devuser/development/electron-api-demos/node_modules/node-fetch/dist/index.cjs:897:8)
at new Request (/Users/devuser/development/electron-api-demos/node_modules/node-fetch/dist/index.cjs:922:17)
at /Users/devuser/development/electron-api-demos/node_modules/node-fetch/dist/index.cjs:1175:19
at new Promise (<anonymous>)
at fetch (/Users/devuser/development/electron-api-demos/node_modules/node-fetch/dist/index.cjs:1173:9)
at IpcMainImpl.<anonymous> (/Users/cbourne/development/electron-api-demos/main-process/communication/async-msg.js:20:36)
at IpcMainImpl.emit (events.js:223:5)
at WebContents.<anonymous> (electron/js2c/browser_init.js:4093:15)
at WebContents.emit (events.js:223:5)
And here's the main-process code I'm testing with:
const {ipcMain} = require('electron')
require('/Users/devuser/development/electron-api-demos/script/wasm_exec.js')
const fetch = require("node-fetch");
ipcMain.on('asynchronous-message', (event, arg) => {
if (!WebAssembly.instantiateStreaming) { // polyfill
WebAssembly.instantiateStreaming = async (resp, importObject) => {
const source = await (await resp).arrayBuffer();
return await WebAssembly.instantiate(source, importObject);
};
}
const go = new Go();
let mod, inst;
WebAssembly.instantiateStreaming(fetch("test.wasm"), go.importObject).then((result) => {
mod = result.module;
inst = result.instance;
document.getElementById("runButton").disabled = false;
}).catch((err) => {
console.error(err);
});
async function run() {
console.clear();
await go.run(inst);
inst = await WebAssembly.instantiate(mod, go.importObject); // reset instance
}
event.sender.send('asynchronous-reply', 'pong')
})
The problem is not WASM at all, but the request that is supposed to get the binary. Your fetch comes from node-fetch; the main process runs in Node.js and as such, does not have a base address like a normal page. Either provide a full file:/// absolute URL to fetch, or, more easily, use fs.readFileSync:
const fs = require('fs');
WebAssembly.instantiate(fs.readFileSync("text.wasm"));
I can only answer part of your question.
WASM should probably not be run in the Main process. Even though WASM will run in an independent thread, you should reduce the load on the Main process to the maximum extent possible. When the Main process is blocked, even something like minimizing your app will not occur until it becomes unblocked.
For more info, this is a good article: https://medium.com/actualbudget/the-horror-of-blocking-electrons-main-process-351bf11a763c
Have you tried changing fetch("test.wasm") to fetch("./test.wasm") or hardcoding a direct path to local file at least for dev purposes?
I have tried this code :
const invNum = require('invoice-number');
router.post('/checkout', async (req, res, next) => {
if (!req.session.cart) {
return res.redirect('/pos/');
}
var saleList = Sale.find().sort({ _id: -1 }).limit(1); // removed (err, data)=>{} to simply view it is working tested already
var settings = await Setting.find({}); // removed try and catch to simply view it is working tested already
var ticketNumber;
ticketNumber = !saleList ? invNum.next('0000000') : invNum.next(saleList.ticket_number);
var sale = new Sale({
ticket_number:ticketNumber,
cart: req.session.cart,
created_at: new Date()
});
sale.save((err, product) => {
createReceipt(settings, req.session.cart, "receipts/"+ticketNumber+".pdf");
req.session.cart = null;
res.redirect('/pos/');
});
});
I got this error:
TypeError: invNum.next is not a function
The problem is with invNum.next().
invNum.next() is a Node.js module to generate invoice number sequentially installed from npm.
Example:
invNum.next('2017/08/ABC001')
// => 2017/08/ABC002
I have tried already suggestions from previous stackoverflow posts by trying Promises or await async function in order to get this code to work. Hopefully, you can help or suggest something. Thank you.
There is a problem in version of invoice-number module. In the npm it is showing as 1.0.6 but in the GitHub repository it has 1.0.5 in the package.json file.
https://github.com/amindia/invoice-number.
I have tested this module by taking from Github repository and it's working fine.
Please take the source of this module from the given link it will works fine.
Seems to be some error in the module. I tried the below code snippet on RunKit
https://runkit.com/embed/ws2lv1y38mt4
var invNum = require('invoice-number')
try{
invNum.next('sdfsd1')
} catch(e){
console.log(e)
}
Getting the same error
I got this error:
TypeError: invNum.next is not a function UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch()
What is the output when you use the console.log on invNum?
Also use try catch and inside call invNum.next with await. Maybe something inside this function is throwing an error.
Edit: as jfriend00 says, if an plain text (like your "0000...") is working, probably the saleList is returning some error and you are not catching or treating the error.
Edit2: The last update on this NPM code is from 1 year ago and fewer people used this lib, probably is broken.
There is some part of the code from the index.js of the lib:
function _next (invoiceNumber) {
if (!invoiceNumber)
throw new Error('invoiceNumber cannot be empty')
var array = invoiceNumber.split(/[_/:\-;\\]+/)
var lastSegment = array.pop()
var priorSegment = invoiceNumber.substr(0, invoiceNumber.indexOf(lastSegment))
var nextNumber = alphaNumericIncrementer(lastSegment)
return priorSegment + nextNumber}
var api = { next: _next}
module.exports = api
I've seen that issue a lot here but none of the solutions worked for me. I'm using NodeJS and had no issue until I changed the project's directory.
Since then I can't get my code to work...
I've included:
import "#babel/polyfill"
I'm using async / await and this is clearly what's causing the issue:
async function process_data(post) {
// my_code
}
If I write the code like that:
const test = async function process_data(post) {
// my code
}
That's working but I can no longer call the process_data method on its own with the parameter (or else, I don't know how do it).
Any idea how I can get that to work?
By tweaking the code I found the answer:
const my_func = async function process_data(post) {
// my code
}
var res = my_func(post_var);
Can anybody help me please. How can i use moment in a formatter?
i think this is not a problem from node or binary parser. it is my understanding i think.
const Parser = require("binary-parser").Parser;
const moment = require('moment');
let time = function(timestamp) {
return moment(timestamp, 'YYMMDDHHmmssSS').format('YYYY-MM-DD HH:mm:ss.SS');
};
let Telegram = new Parser()
.string('timestamp', {encoding: 'hex', length: 7, formatter: time});
The Exception is:
evalmachine.:9
return moment(timestamp, 'YYMMDDHHmmssSS').format('YYYY-MM-DD HH:mm:ss.SS');
^
ReferenceError: moment is not defined
at Parser. (evalmachine.:9:2)
...
I think the Problem is that Parser don't know moment. But how can i realize that?
i have tried to import moment directly in the binary-parser module. But it doesn't working.
If i run moment outside of Parser then it is working.
Maybe anybody can help me.
The formatter function runs without the momentjs context. I am guessing because of the way it consumes the formatter property. In the code found here, the code is:
if (this.code.formatter) {
... (ctx, varName, this.options.formatter)
Because of the funny way the this keyword works, it's bound to the object (options) and because that declaration does not contain momentjs, it says that it is not defined.
You can get a better understanding of this by looking at line 735:
ctx.pushCode("{0} = ({1}).call(this, {0});", varName, formatter);
It's bound to the current object.
P.S.: I copied the code and pasted it on Node.js and it's working perfectly. ^That is a possible explanation.