I want to use systemjs inside react-native.
When I use following code in the browser systemjs register itself with global/window.
fetch('https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.18.17/system.src.js')
.then(response => response.text())
.then(txt => {
eval(txt);
})
.catch(ex => {
console.log(ex);
});
I executed same code in expo AwesomeProject on the homescreen component and the above code does not throw any exceptions, but when I try to render all the globally registered objects I don't see SystemJs/System.
First question I have - Is it even possible to register systemjs and use it with react-native?
If the answer to first question is yes, then is it the correct way to eval(Systemjs)?
If not is there any other method I can use to access system js?
I have seen couple of projects on github like react-native-eval and react auto updater, but that is not what I want.
Anyone can give me some insight?
I will answer my own question.
Yes it is possible to load systemjs in React native.
Simple eval will evaluate the systemjs code, but you might get some errors. I am not an expert in the internals of systemjs but it seems it tries to run in some context, either a browser or in some cases a node server.
I received an error in following code.
var vmModule = 'vm';
var vm = require(vmModule);
I had to tweak my code a little bit and supply a fake require function and I was able to load systemjs.
Related
This question has been asked several times here(here the most relevant,Another example), but no solution has been proposed in any of them. So I have 2 questions to you guys:
Any idea why it wouldn't work in a large project? I mean, there are any know issues with fast refresh related to the size of the project or the packages he includes that will make fast refresh stop working? There is any way to fix it?
Is there a convenient way to edit an internal page in the app without using a fast refresh (without running the page independently, since it depends on all the logic of the app)?
This bug really makes the development really difficult for me, and I find it hard to believe that professional developers have not found a way around this problem, Please help!
I'm using expo-cli(v3.26.2 - Expo SDK 38 that using react-native v0.62)
TLDR;
using default export with no name ALWAYS resulted in a full reload of the app without hot reload!
Details
So after a lot of months of pain, I accidentally found a strangely enough effect:
I usually write my react components in this syntax:
export default ({ ...props }) => {
...
};
and for some reason, changing a module that exports that way ALWAYS resulted in a full reload of the app without hot reload!
after months of pain, accidentally i found out that changing the export to:
const Test = ({ ...props }) => {
...
};
export default Test;
completely fixed the issue and now hot reload works perfectly fine!
I did not saw this effect mentioned in a single place on the internet!
From react-refresh-webpack-plugin troubleshoot section
Un-named/non-pascal-case-named components
See this tweet for drawbacks of not giving component proper names.
They are impossible to support because we have no ways to statically
determine they are React-related. This issue also exist for other
React developer tools, like the hooks ESLint plugin. Internal
components in HOCs also have to conform to this rule.
// Wont work
export default () => <div />;
export default function () {
return <div />;
}
export default function divContainer() {
return <div />;
}
There is an other way to obtain this weird behavior.
When you export a simple function:
//if we export this function in the entry file of the app,
//it will break the hot reload feature without any warnings.
export function someName() {
};
from the entry file of your app (with typescript template expo init nameApp the file is App.tsx)
It will exactly produce a full reload of the app rather than a hot reload.
This is vicious because on ios simulator it full reloads the app without the modification whereas in android it full reloads the app WITH the modification. So you'll take some time to realize that this is not a hot reload in android but a full reload.
IDK why ios don't display the modification like android does..
But when you think at the problem, we shouldn't export multiple things from the entry point of an app. This sounds weird isn't it ?
TLDR;
During development, I had your problem with the infinity "Refreshing..." message. As well as incomprehensible errors like "unknow resolve module 2" and "bundle error..."
Details
the solution turned out to be unexpected, I changed "require()" to "import" in the main index.js file
before
const module = require('some-module')
after
import module from 'some-module';
I've implemented a react-native application and now I want to enhance it by adding along side it another different react-native application.
What i want to achieve is to keep the two application separated in order to continue to implement them as two separate application, and avoid to rewrite them completely as a single application.
Both application are using react-redux to handle their states. The first brutal approach which I have tried is to wrap one of the two application into a npm package and add it as a dependence of the other one. Then I've just added a tab to the main application which when clicked navigate to the second application. This approach seems to work, but I don't think is the best way to do it.
Do you think there could be any sort of problem doing so? Is there a more intelligent and elegant way to do it? I know it is kinda a generic question, so I would accept also an article/link about this argument.
You can create a git tag of your second application and can add it as a dependency in your first application.
You can also add it as a git sub-module.
P.S. i prefer the first one.
I think the best way to do it would be Linking as described here: Basic usage. So, you can easily pass needed parameters to the other app you want to open and also read them as app opens. Check this simple example:
Caller app:
Linking.openURL('calleeApp://app?param1=test¶m2=test2')
Callee app:
componentDidMount() {
Linking.getInitialURL().then((url) => {
if (url) {
console.log('Initial url is: ' + url);
}
}).catch(err => console.error('An error occurred', err));
}
do not forget to import it first:
import { Linking } from "react-native";
Let me know if it worked for you!
I am working with Expo, React Native and I want to to be able to detect text from images. Is there an package i can work with to achieve this?
I am using Expo camera module to snap the picture and supply the URI to the text detector
I have tried using react-native-text-detector but I am getting the error that the function detectFromUri is not defined. I have also tried with tesserect.js but it fails on import with "unable to resolve variable location".
await this.camera.takePictureAsync(options).then(photo => {
photo.exif.Orientation = 1;
//console.log(photo.uri);
const visionResp = await RNTextDetector.detectFromUri(photo.uri);
if (!(visionResp && visionResp.length > 0)) {
throw "UNMATCHED";
}
console.log(visionResp);
});
I am expecting the visionResp to log the results returned from the detection but instead i get undefined is not an object (evaluating '_reactNativeTextDetector.default.detectFromUri')
Is your project created with expo-cli?
If yes, Expo is not supporting OCR currently. There is a feature request on canny.io but you can't know for sure when it will become available.
Your only choice is to use an OCR service like this one.Internet connectivity will be required.
If not, (and the project is created with react-native-cli) you should be able to successfully use react-native-text-detector. Just make sure you link the package correctly. Docs here
I am having an issue related to react-native-asyncstorage from here:
https://facebook.github.io/react-native/docs/asyncstorage.html
When I run react-native run-ios, the following error appears:
I am using react-native 0.52.0 and this problem may be due to the dependency of react-native-asyncstorage:
react-native-asyncstorage#1.0.0 requires a peer of
react-native#^0.47.2 but none is installed. You must install peer
dependencies yourself.
The odd thing is it works fine for Android, but not for both iOS nor iOS emulator.
Can someone help?
EDIT
I would like to add some points that maybe useful:
I use Expo for development,
I have commented every AsyncStorage in my code, but the problem still persist,
As asked in the comment, here is the snipped code of my AsyncStorage code
-
import { AsyncStorage } from 'react-native';
export async function SetItem(strKey, objValue) {
try {
if (typeof(objValue) === 'string') {
await AsyncStorage.setItem(strKey, objValue);
}
else {
await AsyncStorage.setItem(strKey, JSON.stringify(objValue));
}
}
catch(error){
console.log(error);
}
}
Like said in the documentation: NOTE: This is not supported by all native implementations, you're probably running in an error because of this.
It may also be Reactotron you're using (according to the stack trace) that causes this. Try disabling it at first?
Are you having a custom implementation of AsyncStorage (like: https://www.npmjs.com/package/react-native-asyncstorage)? If so, take it off unless there's a specific reason to use it (please elaborate in the question)
But in general, you could for instance use React Native Simple Store and it's update method.
Or then you could write your own function with lodash.merge.
If problem persists even with commenting out all the AsyncStorage code, removing possible custom dependencies and taking off Reactotron, and you can't find a way to write multiMerge by yourself, update your question and ping me on this answer.
The problem here is that I need call MercadoPago in mi Application using React-Native, but i can not find the way,
I found this wrapper for use in React-Native,
https://github.com/shovelapps/react-native-mercadopago
but when I am trying to call it I have an error in startCheckOut method,
I am using in this way the Wrapper
import RNMercadopago from 'react-native-mercadopago';
and I am calling the method in a click event using this line:
RNMercadopago.startCheckout(publicKey, prefId, null, false, (payment) => { this._success(payment)}, (error) => { this._failure(error) });
but I am getting the bellow error,
undefined is not an object (evaluating 'RNMercadopago.startCheckout)
all this code is in the index.ios.js
best regards
you may use react-native-mercadopago-checkout. It allows you to implement MercadoPago checkout in two diferent ways (both of them are documented).
It's a new implementation that is working in a production app. Even, if you find a bug, you could open an Issue and be sure that it will be resolved!