Exercise 1: Save JSON to localStorage
Problem Statement
Create a function `save(key, value)` that JSON stringifies and saves to localStorage.
Sample Output:
save("theme", "dark")
// localStorage.setItem("theme", '"dark"') executed
save("user", {name: "John", age: 30})
// localStorage.setItem("user", '{"name":"John","age":30}') executedSolution
const save = (key, value) => localStorage.setItem(key, JSON.stringify(value));Explanation
Overall Goal:
- JavaScript value ko localStorage me save karna.
- Objects/arrays ko JSON string me convert karke store karna.
Single Line Solution:
const save = (key, value) => localStorage.setItem(key, JSON.stringify(value));
Part 1: Function parameters
(key, value)key→ storage key (string identifier).value→ koi bhi JavaScript value (object, array, number, etc.).
Part 2: JSON stringify
JSON.stringify(value)- JavaScript value ko JSON string me convert karta hai:
{a: 1}→'{"a":1}'[1, 2]→'[1,2]'"hello"→'"hello"'- Why? localStorage sirf strings store karta hai.
Part 3: Store in localStorage
localStorage.setItem(key, ...)- Browser ka localStorage API: persistent storage (tab close ke baad bhi rahega).
setItem(key, value)→ key-value pair store karta hai.
Real world:
- Theme preferences: dark/light mode save.
- User settings: language, currency preferences.
- Form drafts: unsaved data temporarily save.
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