javascript - Read For Learn

Error: Can’t set headers after they are sent to the client

The res object in Express is a subclass of Node.js’s http.ServerResponse (read the http.js source). You are allowed to call res.setHeader(name, value) as often as you want until you call res.writeHead(statusCode). After writeHead, the headers are baked in and you can only call res.write(data), and finally res.end(data). The error “Error: Can’t set headers after they are sent.” means that you’re already in the Body or Finished … Read more

What is this JavaScript “require”?

So what is this “require?” require() is not part of the standard JavaScript API. But in Node.js, it’s a built-in function with a special purpose: to load modules. Modules are a way to split an application into separate files instead of having all of your application in one file. This concept is also present in other languages … Read more

How to set time delay in javascript

Use setTimeout():

Client on Node.js: Uncaught ReferenceError: require is not defined

This is because require() does not exist in the browser/client-side JavaScript. Now you’re going to have to make some choices about your client-side JavaScript script management. You have three options: Use the <script> tag. Use a CommonJS implementation. It has synchronous dependencies like Node.js Use an asynchronous module definition (AMD) implementation. CommonJS client side-implementations include (most of them require a build step before you … Read more

convert Hsl to rgb and hex

New approach (inspired by @Kamil-Kiełczewski solution)Takes degree, percentage, percentage and returns css hex color: Example: Original version: (still OK, just longer) Takes degree, percentage, percentage and returns css hex color: Example:

Toggle show/hide on click with jQuery

Note: This method signature was deprecated in jQuery 1.8 and removed in jQuery 1.9. jQuery also provides an animation method named .toggle() that toggles the visibility of elements. Whether the animation or the event method is fired depends on the set of arguments passed, jQuery docs. The .toggle() method is provided for convenience. It is relatively straightforward … Read more

How do I run code I have written in JavaScript?

open an editor. Simplest one is notepad Write basic HTML there like below<html> <head> </head> <body> Hello World! </body> </html> Add a script tag and write your js inside it like below<html> <head> <script> alert(“hello”); </script> </head> <body> Hello World! </body> </html> or you can write your js code in a file and save as … Read more

How do I copy to the clipboard in JavaScript?

There are three primary browser APIs for copying to the clipboard: Async Clipboard API [navigator.clipboard.writeText] Text-focused portion available in Chrome 66 (March 2018) Access is asynchronous and uses JavaScript Promises, can be written so security user prompts (if displayed) don’t interrupt the JavaScript in the page. Text can be copied to the clipboard directly from a variable. Only … Read more

Difference between npx and npm?

NPM – Manages packages but doesn’t make life easy executing any.NPX – A tool for executing Node packages. NPX comes bundled with NPM version 5.2+ NPM by itself does not simply run any package. it doesn’t run any package in a matter of fact. If you want to run a package using NPM, you must specify that package in your package.json file. When executables are installed via NPM packages, NPM links to … Read more

Use a JSON array with objects with javascript

I have a function that will get a JSON array with objects. In the function I will be able to loop through the array, access a property and use that property. Like this: Variable that I will pass to the function will look like this: Any suggestions how I can solve it?

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