Category: JavaScript Answers

Sometimes, we want to get the domain originating the request in Express.js and JavaScript.

In this article, we’ll look at how to get the domain originating the request in Express.js and JavaScript.

How to get the domain originating the request in Express.js and JavaScript?

To get the domain originating the request in Express.js and JavaScript, we use the host or origina headers or the req.socket.remoteAddress to get the IP address that the request originates from.

For instance, we write

const host = req.get("host");

to get the host header value.

We use

const origin = req.get("origin");

to get the origin header value, which has the host of the originating request for CORS requests.

We get the IP address of the originating request with

const userIP = req.socket.remoteAddress;

req is the request parameter in our route handler or middleware.

Conclusion

To get the domain originating the request in Express.js and JavaScript, we use the host or origina headers or the req.socket.remoteAddress to get the IP address that the request originates from.

Sometimes, we want to get the distance from the top for an element with JavaScript.

In this article, we’ll look at how to get the distance from the top for an element with JavaScript.

How to get the distance from the top for an element with JavaScript?

To get the distance from the top for an element with JavaScript, we get the sum of the window.pageYOffset property and the element’s top value.

For instance, we write

const elDistanceToTop = window.pageYOffset + el.getBoundingClientRect().top;

to use window.pageYOffset to get the vertical offset of the page.

Then we get the element’s computed position values with getBoundingClientRect.

And we use the top property to get the top position of the el element.

We add them together to get el‘s distance from the top of the page.

Conclusion

To get the distance from the top for an element with JavaScript, we get the sum of the window.pageYOffset property and the element’s top value.

Sometimes, we want to set textarea scroll bar to bottom as a default with JavaScript.

In this article, we’ll look at how to set textarea scroll bar to bottom as a default with JavaScript.

How to set textarea scroll bar to bottom as a default with JavaScript?

To set textarea scroll bar to bottom as a default with JavaScript, we set the textarea scrollTop property to the value of the textarea scrollHeight property.

For instance, we write

const textarea = document.getElementById("textarea_id");
textarea.scrollTop = textarea.scrollHeight;

to select the textarea element with getElementById.

Then we set the textarea.scrollTop property to the textarea.scrollHeight value to scroll the textarea to the bottom of it.

Conclusion

To set textarea scroll bar to bottom as a default with JavaScript, we set the textarea scrollTop property to the value of the textarea scrollHeight property.

Sometimes, we want to use split with JavaScript.

In this article, we’ll look at how to use split with JavaScript.

How to use split with JavaScript?

To use split with JavaScript, we call it with the separator string that we want to split the string by.

For instance, we write

const str = "something -- something_else";
const substrs = str.split(" -- ");

to call str.split with the " -- " separator string to split the string by the " -- " string into an array of substrings.

Conclusion

To use split with JavaScript, we call it with the separator string that we want to split the string by.

Sometimes, we want to convert integer array to string array in JavaScript.

In this article, we’ll look at how to convert integer array to string array in JavaScript.

How to convert integer array to string array in JavaScript?

To convert integer array to string array in JavaScript, we call the array map method with String.

For instance, we write

const strs = sphValues.map(String);

to call the array map method with String to convert each value in the sphValues array to strings.

The returned array is assigned to strs.

Conclusion

To convert integer array to string array in JavaScript, we call the array map method with String.