JavaScript & ES6+

Hoisting is JavaScript's default behavior of moving declarations to the top of the current scope. Variables defined with `let` and `const` are hoisted to the top of the block, but not initialized (temporal dead zone).

A closure is a function having access to the parent scope, even after the parent function has closed. Often used to create private variables.

The event loop is a mechanism that allows JavaScript to perform non-blocking operations by offloading operations to the system kernel (Web APIs) whenever possible, orchestrating the Call Stack and the Callback Queue.

`==` checks for value equality with type coercion, whereas `===` checks for strict equality (both value and type must be the same).

Var is function scoped, let and const are block scoped. Let and const are used for declarations that should not be reassigned or redeclared, while var allows for redeclaration.

The 'use strict' directive is used to enable strict mode in JavaScript, which helps catch common coding mistakes and 'unsafe' actions.

A Promise is created using the Promise constructor and passing a callback function that takes two arguments: resolve and reject.

A Map is a data structure that stores key-value pairs, similar to an Object. However, Maps allow for any type of key, not just strings and symbols, and preserve the order of insertion.

The 'finally' block is used to execute code regardless of whether an exception was thrown or caught, and is typically used for cleanup or releasing resources.

The 'for...of' loop is used to iterate over iterable objects such as Arrays, Maps, and Sets, and assigns the value of each property to a variable on each iteration.

'null' represents the absence of a value, while 'undefined' represents an uninitialized variable or a property that does not exist.

A Set is a collection of unique values, and can be created using the Set constructor and adding values using the 'add' method.

The 'Object.freeze' method is used to freeze an object, making it immutable and preventing any changes to its properties.

The 'Array.prototype.find' method is used to find the first element in an array that satisfies a provided testing function.

'==' checks for loose equality, while '===' checks for strict equality, also known as identity.

The 'Array.prototype.reduce' method is used to apply a function to each element in an array and reduce it to a single value.

The 'Symbol' data type is used to create unique and immutable values that can be used as property keys in objects.

The 'async/await' syntax is used to write asynchronous code that is easier to read and maintain, by using the 'async' keyword to declare a function that returns a Promise, and the 'await' keyword to pause execution until a Promise is resolved.

'console.log' is used to output a message to the console, while 'console.debug' is used to output a debug message to the console, which can be filtered out.

A Proxy object is used to create a virtualized representation of an object, and can be used to intercept and modify the behavior of an object.

The 'Reflect' object is used to provide a way to intercept and modify the behavior of an object, and provides methods for common operations such as getting and setting properties.

The 'Atomics' object is used to provide a way to perform atomic operations on SharedArrayBuffers, which can be used to share data between threads.

'setTimeout' is used to execute a function after a specified delay, while 'setInterval' is used to execute a function repeatedly at a specified interval.

A WeakMap is a data structure that stores key-value pairs, where the keys are weakly referenced, meaning they can be garbage collected if no other references to the key exist.

The 'Intl' object is used to provide a way to perform internationalization and formatting of data, such as dates, numbers, and currencies.