Category: JavaScript Answers

Sometimes, we want to do fade-in and fade-out with JavaScript and CSS.

In this article, we’ll look at how to do fade-in and fade-out with JavaScript and CSS.

How to do fade-in and fade-out with JavaScript and CSS?

To do fade-in and fade-out with JavaScript and CSS, we use the transition CSS property.

For instance, we write

<button id="handle">Fade</button>
<div id="slideSource">Whatever you want here - images or text</div>

to add a button and the div we want to element.

Then we write

#slideSource {
  opacity: 1;
  transition: opacity 1s;
}

#slideSource.fade {
  opacity: 0;
}

to add the transition effects with the transition property.

We animate the opacity between 0 and 1.

Then we write

const slideSource = document.getElementById("slideSource");

document.getElementById("handle").onclick = () => {
  slideSource.classList.toggle("fade");
};

to select the div with getElementById.

And then we select the button and set its onclick property to a function that toggles the fade class to animate the opacity between 1 and 0 and vice versa when we click on it.

Conclusion

To do fade-in and fade-out with JavaScript and CSS, we use the transition CSS property.

Sometimes, we want to get path from the request with Node.js and JavaScript.

In this article, we’ll look at how to get path from the request with Node.js and JavaScript.

How to get path from the request with Node.js and JavaScript?

To get path from the request with Node.js and JavaScript, we use the request.url property.

For instance, we write

const http = require("http");
const url = require("url");

const start = () => {
  const onRequest = (request, response) => {
    const pathname = url.parse(request.url).pathname;
    console.log(pathname);
    response.writeHead(200, { "Content-Type": "text/plain" });
    response.write("Hello World");
    response.end();
  };

  http.createServer(onRequest).listen(8888);
  console.log("Server has started.");
};

exports.start = start;

to get the path name of the request URL with url.parse(request.url).pathname.

Conclusion

To get path from the request with Node.js and JavaScript, we use the request.url property.

Sometimes, we want to define a regular expression that allows letters, numbers, and spaces with at least one letter or number with JavaScript.

In this article, we’ll look at how to define a regular expression that allows letters, numbers, and spaces with at least one letter or number with JavaScript.

How to define a regular expression that allows letters, numbers, and spaces with at least one letter or number with JavaScript?

To define a regular expression that allows letters, numbers, and spaces with at least one letter or number with JavaScript, we add all the required patterns in the regex.

For instance, we write

/^[ _]*[A-Z0-9][A-Z0-9 _]*$/;

to add [ _] to check for spacers.

And we use [A-Z0-9][A-Z0-9 _] to check for at least 1 number or letter.

Conclusion

To define a regular expression that allows letters, numbers, and spaces with at least one letter or number with JavaScript, we add all the required patterns in the regex.

Sometimes, we want to change a select value from JavaScript.

In this article, we’ll look at how to change a select value from JavaScript.

How to change a select value from JavaScript?

To change a select value from JavaScript, we set the selectedIndex or value property.

For instance, we write

<select id="select">
  <option value="defaultValue">Default</option>
  <option value="Option1">Option1</option>
  <option value="Option2">Option2</option>
</select>

to add a select element.

Then we write

document.getElementById("select").selectedIndex = 0;
document.getElementById("select").value = "defaultValue";

to select the select element with getElementById.

Then we set the first option as the value by setting selectedIndex to 0 or setting value to 'defaultValue'.

Conclusion

To change a select value from JavaScript, we set the selectedIndex or value property.

Sometimes, we want to clear the content of an iframe with JavaScript.

In this article, we’ll look at how to clear the content of an iframe with JavaScript.

How to clear the content of an iframe with JavaScript?

To clear the content of an iframe with JavaScript, we call write to write an empty string.

For instance, we write

const iframe = document.getElementById("myiframe");
const html = "";

iframe.contentWindow.document.open();
iframe.contentWindow.document.write(html);
iframe.contentWindow.document.close();

to select the iframe with getElementById.

Then we call open to open the iframe’s document.

Next, we call write to clear the iframe’s document.

And then we call close to close it.

Conclusion

To clear the content of an iframe with JavaScript, we call write to write an empty string.