How do I correctly clone a JavaScript object?

I have an object x. I’d like to copy it as object y, such that changes to y do not modify x. I realized that copying objects derived from built-in JavaScript objects will result in extra, unwanted properties. This isn’t a problem, since I’m copying one of my own literal-constructed objects. How do I correctly clone a JavaScript object? Answer To do this for any object in JavaScript will not be simple or straightforward. You will run into the problem of erroneously picking up attributes from the object’s prototype that should be left in the prototype and not copied to

How to load up CSS files using Javascript?

Is it possible to import css stylesheets into a html page using Javascript? If so, how can it be done? P.S the javascript will be hosted on my site, but I want users to be able to put in the <head> tag of their website, and it should be able to import a css file hosted on my server into the current web page. (both the css file and the javascript file will be hosted on my server). Answer Here’s the “old school” way of doing it, which hopefully works across all browsers. In theory, you would use setAttribute unfortunately

What is the scope of variables in JavaScript?

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally? Answer TLDR JavaScript has lexical (also called static) scoping and closures. This means you can tell the scope of an identifier by looking at the source code. The four scopes are: Global – visible by everything Function – visible within a function (and its sub-functions and blocks) Block – visible within a block (and its sub-blocks) Module – visible within a module Outside

What is the preferred syntax for defining enums in JavaScript?

What is the preferred syntax for defining enums in JavaScript? Something like: Or is there a more preferable idiom? Answer Since 1.8.5 it’s possible to seal and freeze the object, so define the above as: or and voila! JS enums. However, this doesn’t prevent you from assigning an undesired value to a variable, which is often the main goal of enums: One way to ensure a stronger degree of type safety (with enums or otherwise) is to use a tool like TypeScript or Flow. Source Quotes aren’t needed but I kept them for consistency.

How can I beautify JavaScript code using Command Line?

I am writing a batch script in order to beautify JavaScript code. It needs to work on both Windows and Linux. How can I beautify JavaScript code using the command line tools? Answer First, pick your favorite Javascript based Pretty Print/Beautifier. I prefer the one at http://jsbeautifier.org/, because it’s what I found first. Downloads its file https://github.com/beautify-web/js-beautify/blob/master/js/lib/beautify.js Second, download and install The Mozilla group’s Java based Javascript engine, Rhino. “Install” is a little bit misleading; Download the zip file, extract everything, place js.jar in your Java classpath (or Library/Java/Extensions on OS X). You can then run scripts with an invocation

How can I remove a child node in HTML using JavaScript?

Is there a function like document.getElementById(“FirstDiv”).clear()? Answer To answer the original question – there are various ways to do this, but the following would be the simplest. If you already have a handle to the child node that you want to remove, i.e. you have a JavaScript variable that holds a reference to it: Obviously, if you are not using one of the numerous libraries that already do this, you would want to create a function to abstract this out: EDIT: As has been mentioned by others: if you have any event handlers wired up to the node you are