To add a required input with React, we add the required prop to the input.
For instance, we write
<input required />
to add an input with the required prop to make it a required input.
Category: JavaScript
To fix ‘property was accessed during render but is not defined on instance.’ error with Vue.js, we should make sure what’s referenced in the template is registered as a prop or defined as a reactive property.
For instance, we write
<template>
<span>{{ name }}</span>
</template>
<script>
export default {
name: "NameComponent",
data() {
return {
name: ""
};
}
</script>
to define the NameComponent component that has the name reactive property as defined in the object returned by the data method.
Then we reference name in the template to render name‘s value.
To cancel a promise with JavaScript, we use the AbortController constructor.
For instance, we write
const controller = new AbortController();
const task = new Promise((resolve, reject) => {
//...
controller.signal.addEventListener("abort", () => {
reject();
});
});
controller.abort();
to create an AbortController object.
Then we create the promise with the Promise constructor called with a callback.
In it, we listen to the abort controller’s abort event by calling controller.signal.addEventListener in the task promise.
We call it with a callback that calls reject to reject the promise, which stops the promise from running.
Then we call controller.abort to cancel the promise, which triggers the abort event on the controller.
To add React file download with JavaScript, we create a link.
And then we can create a hidden link that has the blob’s object URL set as the href attribute and click on the link programmatically to download it.
For instance, we write:
import React from "react";
export default function App() {
const downloadFile = () => {
const element = document.createElement("a");
element.href = url;
element.download = "filename";
document.body.appendChild(element);
element.click();
};
return (
<div>
<button onClick={downloadFile}>Download txt</button>
</div>
);
}
to define the downloadFile function to put the 'hello world' string in a blob and download that as a text file.
In the function, we create an a element with document.createElement.
Next, we set element.href to the fil’s URL.
And we set the file name of the downloaded file by setting the element.download property.
Next, we call document.body.appendChild with the link element to attach it to the body.
Finally, we call element.click to click on the hidden link to download the file.
To add a React video background, we can add the loop, autoPlay and muted props to the video element.
For instance, we write:
import React from "react";
export default function App() {
return (
<div>
<video autoPlay loop muted>
<source
src="https://file-examples-com.github.io/uploads/2017/04/file_example_MP4_480_1_5MG.mp4"
type="video/mp4"
/>
</video>
</div>
);
}
We have autoPlay loop muted added to the video element so that the video plays automatically, repeats when it finishes playing, and it’s muted respectively.
In it, we add the source element with the src attribute set to the URL of the video we want to play in the background.
We add the loop prop to make it restart when the video is finished playing.
The muted prop mutes the video.
As a result, we have a video that loops forever silently on the page.