1- 𝗡𝘂𝗹𝗹𝗶𝘀𝗵 𝗰𝗼𝗮𝗹𝗲𝘀𝗰𝗶𝗻𝗴 𝗼𝗽𝗲𝗿𝗮𝘁𝗼𝗿 (??) accepts two operands and return the right operand if the left one is null or undefined.

console.log(false ?? 'hellooo') //false
console.log(null ?? 'hellooo') //'hellooo'
console.log(null || 'hellooo') //'hellooo'
console.log((false || null) ?? 'hellooo') // 'hellooo'
console.log(null ?? (false || 'hellooo')) // 'hellooo'

2- 𝗢𝗽𝘁𝗶𝗼𝗻𝗮𝗹 𝗰𝗵𝗮𝗶𝗻𝗶𝗻𝗴 𝗼𝗽𝗲𝗿𝗮𝘁𝗼𝗿 (?.) Simplify the way to access a property located deep within a chain of connected objects. Eg: Pokemon && Pokemon.raichu can be written as Pokemon?.raichu

3- 𝗣𝗿𝗼𝗺𝗶𝘀𝗲.𝗮𝗹𝗹𝗦𝗲𝘁𝘁𝗹𝗲𝗱() accepts a list of promises and returns a new promise that resolves to an array of values, which were settled (either resolved or rejected) by the input promises.

4- 𝗗𝘆𝗻𝗮𝗺𝗶𝗰 𝗜𝗺𝗽𝗼𝗿𝘁 - The import allows you to dynamically import a module when needed. The import() returns a Promise that will be fulfilled once the module is loaded completely.

5- 𝗕𝗶𝗴𝗜𝗻𝘁 a new primitive type that can represent whole numbers bigger than 2^53 - 1, which is the largest number Javascript can reliably represent with the Number type. To make a BigInt, you append 𝒏 to the end of an integer literal.

3 + 4 + 1n // ERROR! as BigInts need to be calculated with other BigInts.
3n + 4n + 1n //  8n
3 + 4 + 1 //  8 
// Both produce the value of 8, but one is a Number type, the other is a BigInt type

6- 𝗴𝗹𝗼𝗯𝗮𝗹𝗧𝗵𝗶𝘀 - If you write code that needs to access the global object, use different syntaxes like window, frames, self, or global. To standardize this, ES2020 introduced the globalThis available across environments.

That's all, folks.
Happy Hustling!