I am trying to use jquery.infinitedrag to create a component in react. My code is here:
//Grid.js
import React from 'react'
import './jquery/jquery.min.js'
import './jquery/jquery-ui.min.js'
import './jquery/jquery-ui.min.css'
import './jquery/jquery.infinitedrag.js'
export default class Grid extends React.Component{
componentDidMount() {
$.infinitedrag("wall")
}
render() {
return(
<div id="wall"/>
)
}
}
This is supposed to work by making a div (identified by id) when react renders and then filling in an infinite grid later once the component mounts. The problem is, for some reason, jquery.infinitedrag is getting confused. Here is the error:
Failed to compile.
./src/jquery/jquery.infinitedrag.js
Line 108:4: Expected an assignment or function call and instead saw an expression no-unused-expressions
Line 277:4: 'jQuery' is not defined no-undef
My file structure looks like this:
src
-jquery
-jquery.min.js
-jquery-ui.min.js
-jquery-ui.min.css
-jquery.infinitedrag.min.js
-Grid.js
-misc other components and stuff
I am fairly new to javascript, so this is probably something dumb.
npm install jquery OR npm update to remove the second error.
Related
New to React JS, props validation practise as follows:
import React from 'react';
import PropTypes from 'prop-types';
class App extends React.Component {
render() {
return (
<div>
<h3>String : {this.props.propstring}</h3>
</div>
);
}
}
App.propTypes = {
propstring : PropTypes.string
}
App.defaultProps = {
propstring : "My Name"
}
export default App;
import React, { component } from 'react';
import ReactDOM from 'react-dom';
import App from './AppProp.js';
ReactDOM.render(<App />,document.getElementById('root'));
Getting an error as:
TypeError: Class extends value undefined is not a constructor or null.
What am I missing here and how can I resolve the above error?
There are 2 possible problems. Most probably you're importing { component }(like you do in your index file, which is wrong), instead of { Component } somewhere in your code and trying to extend component which doesn't exist.
The other reason is that you might be circularly importing classes, but I doubt it. Also, is your file called AppProp.js?
Post the stack trace and it would also help if you post all the components you're using. Post your package.json as well, as you might be using wrong absolute paths.
The code is perfectly fine. I executed it on my local machine and it ran fine.
The only issue you may be facing is to with
circularly importing classes, which is apparently a limitation
Know more from the resource:
https://esdiscuss.org/topic/how-to-solve-this-basic-es6-module-circular-dependency-problem
Following Programming with Mosh's React tutorial and stuck on this very initial portion after installing everything, bootstrap, popper, etc. Deleted package json lock and double checked spelling. For whatever reason no matter what, it is failing to compile and I get the same error every time:
"Module not found: Can't resolve './components/counter.jsx'
Picture of my terminal and vscode
Picture of my errors in dev tools
I really am stuck on this portion and could use help figuring out what the issue is.
import React, { Component } from "react";
class Counter extends Component {
state = {};
render() {
return <h1>Hello World</h1>;
}
}
export default Counter;
In his tutorial he has changed the JSX file name from counter.jsx to counterComponent.jsx. Import as below:
import Counter from './components/counterComponent'
When importing components and other javascript modules, you shouldn't provide the file extension. Try and remove the .jsx from the import so it says:
import Counter from "./components/counter";
For context, let me try to explain a little more.
In my project I have a folder, as example, for components.
Inside that folder I have my components files, and an index.js file where I import all the components and export than in the same line as follows:
export { default as Button } from './button'
export { default as Loader } from './loader'
export { default as ImageBackground } from './image-background'
So than I can import these components in Screen Component like that:
import { Button, Loader, ImageBackground } from 'src/components'
If I edit the components file, save and reload the project, everything works fine.
The problem is that when I edit any of these components with the Hot Module Replacement (Hot Reloading) actived, when it is triggered after an edit, it throws the following error:
Unhandled JS Exception: Requiring module "src/components/index.js", which threw an exception: TypeError: Cannot redefine property: Button
Has anyone have any idea why this is happening?
Thanks in advance!
Obs: When I import the component direct without using the index.js or if inside the index.js, I first import the component, than I assign the component to a variable and than I export this variable, it works fine.
my problem was solved when I changed render = () => (...) to render(){ return (...)} in react component
I am trying to add PrismJS as syntax highliter in my Aurelia app (typescript based) and I am half way there as below
1- Install prismjs
yarn add prismjs
2- add css & code part
<template>
<require from="prismjs/themes/prism.css"></require>
<pre><code class="language-sql">${highlightedSQL}</code></pre>
</template>
3- import the prismjs in the component and call highlite.
import "prismjs";
import prismsql from "prismjs/components/prism-sql";
let Prism; // very weird, I have to declare a global variable, other wise it won't work(typescript error)
#inject(HttpClient)
export class Detail {
highlight() {
this.highlightedSQL = Prism.highlight(data.sql, Prism.languages.sql, 'sql');
}
}
and I am getting this error
Unhandled rejection TypeError: Cannot read property 'highlight' of undefined
what could be the right way to make it work?
ill post my comment as an answer just to have the question closed.
instead of import "prismjs"; and let Prism; you should have import Prism from 'prismjs';
My broader question is does an import of a module get shared between two components and why?
First what do I know about import. You can import in two different ways.
1.
At the top of your file which loads the imported module into a variable which you then can use.
import Highcharts from './highcharts'
// create a chart
Highcharts.Chart()
2.
Or dynamically anywhere in your code which returns a promise:
import('./highcharts').then((response) => {
// create chart
response.Chart();
});
But there is this weird behavior I don't understand when using import with react. If I have the following component:
import React, {Component} from 'react';
import Highcharts from 'highcharts/js/highcharts';
export default class Chart extends Component {
state = {
chartOptions: {
// my chart options and data
}
}
componentDidMount() {
if(this.props.extendFunc) {
import('highcharts/js/modules/funnel.src.js').then((funnelModule) => {
funnelModule(Highcharts)
})
}
Highchart.Chart('myChart', this.state.chartOptions)
}
render() {
<div id="myChart" />
}
}
I use the component from above twice. Now there is this behavior that both components use the same import e.g. the import of Highcharts does not happen twice. I noticed this because with Highcharts there is the option of extending the functionality.
If I for example extend the functionality for Chart 1 by passing a prop to extend it, the functionality of Highcharts is also extended in Chart 2, although I didn't pass a prop to extend the functionality.
import React, {Component} from 'react';
import Chart from './Chart';
export default class Dashboard extends Component {
render() {
return (
<div>
<Chart extendFunc={true}> Chart 1 </Chart>
<Chart> Chart 2 </Chart>
</div>
)
}
}
What causes this behavior? Is this react or is this just the way import works? Are imports global for multiple instances of the same component? Or are imports of a node module the same for the whole application?
What causes this behavior? Is this react or is this just the way import works? Are imports global for multiple instances of the same component? Or are imports of a node module the same for the whole application?
This is the way imports work. When you import something for the first time, the file is run and the exported values from it are returned back to the one importing it. When something is imported again, those same exports are reused and returned. Node JS modules work the same way.
Sometimes this behavior is helpful, firstly for performance to avoid unnecessarily re-running the same file over again, and also if the module wants to store some internal state. For example, counting the number of times a function is called from anywhere in the application.
In cases like this, where you need a single instance of something for each script, modules will usually give you a way to actually make an instance of that thing. For example, I might have a logging module, which exports a Logger class, then I can make new instances of that class for each component, and configure each logger separately.
For your case, look in the docs to see if there's a way to make per-component instances of Highcharts and extend that individual instance with the functionality you need.
When you extend <Chart /> with a prop extendFunc it will be extended in your Chart Component and not in your "new" Component.
That means, if you call the component, it will always have the props you gave it, but you will not have to use them (if there are not set as required).