Web developer specializing in React, Vue, and front end development.
To change an ISO date string to a JavaScript date object, we can use the Date constructor to convert it to a JavaScript date object.
For instance, we can write:
const d = new Date('2021-11-03T19:00:34.203Z');
const n = d.getUTCDate();
We just pass the ISO date string as the argument of the Date constructor.
Then we call getUTCDate to return the date of the month in UTC.
Therefore, n is 3.
To create an HTML canvas with JavaScript, we can use the document.createElement method.
For instance, we can write:
const canvas = document.createElement('canvas');
canvas.width = 100;
canvas.height = 100;
document.body.appendChild(canvas)
const ctx = canvas.getContext("2d");
We call document.createElement with 'canvas' to create a canvas element.
Then we set its width and height by setting the width and height properties.
Next, we call document.body.appendChild with canvas to attach it to the body element as its child.
Finally, we call canvas.getContext to get the 2d context.
To add DOM elements with jQuery, we can use the jQuery appendTo method.
For instance, if we want to add an anchor element to the body element, we write:
$("<a/>", {
id: 'link',
href: 'http://www.example.com/',
text: 'Example Page'
}).appendTo("body");
We call $ with '<a/>' to create a new element.
The 2nd argument we passed into $ are the attributes and the values of the element.
Then we call appendTo on the returned object with 'body' to attach the element to body.
To access a camera from a browser with JavaScript, we can use the WebRTC API to access the camera when permission is granted.
To do this, we write:
const video = document.createElement("video");
video.setAttribute("playsinline", "");
video.setAttribute("autoplay", "");
video.setAttribute("muted", "");
video.style.width = "200px";
video.style.height = "200px";
const facingMode = "user";
const constraints = {
audio: false,
video: {
facingMode
}
};
navigator.mediaDevices.getUserMedia(constraints).then((stream) => {
video.srcObject = stream;
});
document.body.appendChild(video);
to create a video element with some attribute with:
const video = document.createElement("video");
video.setAttribute("playsinline", "");
video.setAttribute("autoplay", "");
video.setAttribute("muted", "");
video.style.width = "200px";
video.style.height = "200px";
We set the width, height, autoplay attribute, and more with setAttribute and setting style properties.
Then we call navigator.mediaDevices.getUserMedia with the constraints to access the camera.
audio is set to false to disable picking up audio.
And video.facingMode is set to 'user' to let the code access the front camera.
Once the camera can be accessed, the then callback is run, and the video.srcObject is set to the stream to disable what the camera picks up onto the screen via the video element.
Finally, we call document.body.appendChild with video to display the video element onto the screen.
Now once we granted permission for the code to access the camera, we should see the stuff picked up by the front camera on the browser’s screen.
Sometimes, we want may run into the problem where the colspan attribute isn’t being rendered with React.
In this article, we’ll look at how to fix the problem where the colspan attribute isn’t being rendered with React.
To fix the problem where the colspan attribute isn’t being rendered with React, we should make sure we use colSpan instead of colspan as the attribute name.
Also, the attribute value should be a number.
For instance, we should write:
export default function App() {
return (
<table border={1}>
<tbody>
<tr>
<th colSpan={2}>animal are...</th>
</tr>
<tr>
<td>monkeys</td>
<td>donkeys</td>
</tr>
</tbody>
</table>
);
}
to make sure that colSpan is added instead of colspan and 2 is in braces instead of quotes so it’s interpreted as a number.
Now the colspan should be rendered correctly.
To fix the problem where the colspan attribute isn’t being rendered with React, we should make sure we use colSpan instead of colspan as the attribute name.