QJavaScript · Interview preparation
What is object destructuring in JavaScript?
Destructuring binds selected properties to local variables and can provide default values.
The idea to remember.
Destructuring binds selected properties to local variables and can provide default values. It keeps parameter handling readable, but defaults apply when a property is undefined, not when it is null.
01Learn by doing
From first example to real project.
Start with the smallest working idea, examine a more detailed example, then look at a real application pattern. Adapt dependencies, error handling and data models to your project.
Basic: understand this
01 / BEGINNERThe call site determines this for ordinary functions.
const account = {
balance: 10,
show() { return this.balance; }
};
console.log(account.show()); // 10Intermediate: copy before changes
02 / INTERMEDIATESpread makes a shallow copy; nested objects still share references.
const user = { name: 'Ava', settings: { dark: false } };
const updated = { ...user, settings: { ...user.settings, dark: true } };Real scenario: normalize API data
03 / REAL SCENARIOMake defaults explicit at an untrusted API boundary.
function normalizeUser(data) {
return {
id: String(data.id),
name: typeof data.name === 'string' ? data.name : 'Guest'
};
}02Check your understanding
Try it in your own words.
Explain what is object destructuring in JavaScript without looking at the code. Then modify the intermediate example, describe one trade-off and identify when the real-world pattern fits.
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