🧩 JavaScript Quiz
In JavaScript, which keyword is used to declare a variable that cannot be reassigned after its initial value is set?
In JavaScript, which keyword is used to declare a variable that cannot be reassigned after its initial value is set?
Anonymous Quiz
15%
let
5%
immutable
69%
const
11%
var
localStorage Persistence: The Silent Bank Vault
What’s happening?
localStorage is like a browser’s hard drive. It survives tab/window closures, even system reboots.
Unlike sessionStorage (which dies with the tab), localStorage sticks until explicitly cleared (localStorage.clear() or user clears browsing data).
Gotcha: It’s synchronous meaning it blocks the main thread if you store large data.
What’s happening?
localStorage is like a browser’s hard drive. It survives tab/window closures, even system reboots.
Unlike sessionStorage (which dies with the tab), localStorage sticks until explicitly cleared (localStorage.clear() or user clears browsing data).
Gotcha: It’s synchronous meaning it blocks the main thread if you store large data.
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JavaScript Event Loop: The Truth About setTimeout(0)
The Real Order of Operations:
1. Call Stack: Synchronous code (A, D) - This is where JavaScript executes code sequentially, like reading a script.
2. Microtasks: Promises (C) - These are small tasks that need to be executed ASAP after the current script, before the next rendering. Think of them as urgent side tasks.
3. Macrotasks: Timeouts/Intervals (B) - These are longer tasks that the browser queues up to do whenever it gets a chance. They're not as urgent as microtasks.
Golden Rule: "0ms" doesn't mean immediate - it means "next event loop tick".
The Real Order of Operations:
1. Call Stack: Synchronous code (A, D) - This is where JavaScript executes code sequentially, like reading a script.
2. Microtasks: Promises (C) - These are small tasks that need to be executed ASAP after the current script, before the next rendering. Think of them as urgent side tasks.
3. Macrotasks: Timeouts/Intervals (B) - These are longer tasks that the browser queues up to do whenever it gets a chance. They're not as urgent as microtasks.
Golden Rule: "0ms" doesn't mean immediate - it means "next event loop tick".
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