From ES6, there are Proxy and Reflect classes which allow us to customize the objects at several language levels. For example: property retrieval, assignment, iteration, function invocation, ... Lets start with several samples. Example 1: Programmable property retrievalLets see an example that you want an

Check if a value is array type To check whether an object is array type, use Array.isArray(), instead of instanceof Array. Reason: instanceof Array does not work across realms ( window, iframe). Check here, and here. Note that a TypedArray (e.g., new Int8Array(

TLDR; With an ES6 Map, use for (const [key, value] of myMap), this is equivalent to for (const [key, value] of myMap.entries()).With an ES6 Set, use for (const value of mySet), this is equivalent to for (const value of mySet.values()).With

In Javascript, object's property falls into exactly one of two categories (not both, not none of them): data property, accessor property (ECMA). DefinitionRegardless of with or without your explicit definition, all object's properties have their associated property descriptor, which have the following properties. (both

How does the new operator work in Javascript, when for example, calling new MyClass(...params)? Step 1: create a new object by Object.create(MyClass.prototype).Step 2: call MyClass's constructor function (the MyClass itself iff it is a function) with this set as

When it happens that you want to find the first pair of elements from two arrays. You would want to break the for-loop after the predicate is satisfied. The common approach is introducing a flag and check after each iteration in the outer loop.

This post explains how javascript does when it compares two values with a relational operator ( <, >, <=, >=). If you are looking for equality comparison ( ==, ===), check this post instead. Abstract Relational Comparison algorithmThe relation comparison in Javascript mainly follows the Abstract Relational Comparison

TLDR; The list of required permissions is as follows: These include BatchCheckLayerAvailability, GetAuthorizationToken, CompleteLayerUpload, InitiateLayerUpload, PutImage, and UploadLayerPart. This is the role's detail in JSON format. { "Version": "2012-10-17", "Statement": [ { "Sid": "VisualEditor0", "Effect": "Allow", "Action": [ "ecr:CompleteLayerUpload", "ecr:UploadLayerPart", "ecr:InitiateLayerUpload", "ecr:BatchCheckLayerAvailability", "ecr:PutImage"

TLDR; With docker installed, this command can be be used to access the mysql server without installing the mysql client. docker run -it --rm mysql mysql -u <your-account> -p<your-password> -h <your-host> [<your-database-name>]

List of various tar commands for your daily uses. Create an (uncompressed) archive.Create: tar cvf data.tar data/Extract: tar xvf data.tar2. Create and compress in xz format Note: xz = LZMA = Lempel–Ziv–Markov chain algorithm Create: tar Jcvf data.tar.xz

The title's full phrase is Dots Per Inch versus Pixels Per Inch versus Device Dots Per Pixel. Dots Per Inch (DPI): only used for physical printing, which specifies how many color dots are printed in one-pixel length. This number mostly presents the ability of

As the title suggests, what is the difference between authentication and authorization? Authentication: the process to confirm who you are.You are going to persuade the server that you are the user with the username foo by including your account password bar. The process

TLDR; Here is the code export const usePrevRef = <T>(value: T) => { const currentRef = useRef<T>() const prevPref = useRef<T>() prevPref.current = currentRef.current currentRef.current = value return prevPref }Why do we need two refs to accomplish such

Everything about inotify in Ubuntu. Check current config$ sysctl fs.inotify fs.inotify.max_queued_events = 16384 fs.inotify.max_user_instances = 128 fs.inotify.max_user_watches = 65536To modify the configuration permanently. sudo vim /etc/sysctl.conf, modify these following lines or add

In Javascript, in general, to check if a variable is undefined or omitted, we usually use typeof x === 'undefined'. However, sometimes you need to go further and differentiate these two cases, that if a variable is assigned with the undefined value or is omitted/

In this tutorial, I will introduce step by step how to setup a full-fledge email server. At the end of the tutorial, the email server will support SMTP server to receive emailSMTP to send emailReceiving SMTP server supports TLSSending SMTP server support DKIMConfigure DMARC,

I will introduce several useful commands in Ubuntu to manipulate users and groups. Group manipulations (3 commands)List all groups: groupsAdd a new group: groupadd <new group name>Remove a group: groupdel <group name>User manipulations (5 commands)My username:

To run the AppImage package, it is effortless. Everything we need to do is making the package file executable with chmod +x <appname>.AppImage. On the other hand, if you want to make a desktop shortcut to the program, or pin it

In my NVIDIA card-attached PC, the NVIDIA graphic driver always fails to start every time the Linux kernel is upgraded. Whenever I upgrade the kernel version, after a PC restart, the second display cannot connect. I tried running nvidia-smi, it shows an error message