To enable CORS in a React App with Node.js backend, we use the cors package.
To install it, we run
npm i cors
Then we use it by writing
const express = require("express");
const request = require("request");
const cors = require("cors");
const app = express();
app.use(cors());
app.use("/", (req, res) => {
//...
});
app.listen(80, () => {
console.log("CORS-enabled web server listening on port 80");
});
We add the cors middleware with
app.use(cors());
to enable CORS
To get row item on checkbox selection in React MUI DataGrid, we set the onSelectionModelChange prop to a function to get the selected items.
For instance, we write
const App = () => {
//...
return (
<>
<DataGrid
rows={rows}
onSelectionModelChange={(ids) => {
const selectedIDs = new Set(ids);
const selectedRowData = rows.filter((row) =>
selectedIDs.has(row.id.toString())
);
console.log(selectedRowData);
}}
>
...
</DataGrid>
</>
);
};
export default ThemeSelector;
to set onSelectionModelChange to a function that gets the select row IDs from the ids parameter.
Then we can get the selected rows with
const selectedRowData = rows.filter((row) =>
selectedIDs.has(row.id.toString())
);
To add conditional CSS in create-react-app, we can load CSS files dynamically.
For instance, we write
import React from "react";
const Theme1 = React.lazy(() => import("./Theme1"));
const Theme2 = React.lazy(() => import("./Theme2"));
const ThemeSelector: React.FC = ({ children }) => (
<>
<React.Suspense fallback={() => null}>
{shouldRenderTheme1 && <Theme1 />}
{shouldRenderTheme2 && <Theme2 />}
</React.Suspense>
{children}
</>
);
export default ThemeSelector;
to import the Theme1 and Theme2 CSS files with
const Theme1 = React.lazy(() => import("./Theme1"));
const Theme2 = React.lazy(() => import("./Theme2"));
Then we render Theme1 or Theme2 according to the values of shouldRenderTheme1 and shouldRenderTheme2
Sometimes, we want to dynamically load a stylesheet with React.
In this article, we’ll look at how to dynamically load a stylesheet with React.
To dynamically load a stylesheet with React, we can add a link element with the attributes we want.
For instance, we write:
import React, { useState } from "react";
export default function App() {
const [stylePath] = useState(
"https://cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min.css"
);
return (
<div>
<link rel="stylesheet" type="text/css" href={stylePath} />
</div>
);
}
to create the stylePath state with the useState hook.
Its initial value is set to the URL of the stylesheet that we want to include.
Then we add a link element with the href prop set to stylePath to add the stylesheet at the given URL into the component.
To dynamically load a stylesheet with React, we can add a link element with the attributes we want.
Sometimes, we want to map only a portion of an array to components in a React component.
In this article, we’ll look at how to map only a portion of an array to components in a React component.
To map only a portion of an array to components in a React component, we can use the JavaScript array’s filter method to return an array of the items we want to map before calling map.
For instance, we write:
import React from "react";
export default function App() {
const feed = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
return (
<div>
{feed
.filter((item) => item <= 5)
.map((filteredItem) => (
<p key={filteredItem}>{filteredItem}</p>
))}
</div>
);
}
to create the feed array.
And we want to display the first 5 entries from feed.
To do this, we call filter with (item) => item <= 5 to return the first 5 elements.
Then we call map with a callback to return p elements with the content of the elements to display them on the screen.
Now we see:
1
2
3
4
5
on the screen
To map only a portion of an array to components in a React component, we can use the JavaScript array’s filter method to return an array of the items we want to map before calling map.