QJavaScript · Interview preparation
What are the limitations of JSON.stringify?
JSON.stringify cannot represent every JavaScript value faithfully: undefined, functions, special numeric values and cycles need special handling.
The idea to remember.
JSON.stringify cannot represent every JavaScript value faithfully: undefined, functions, special numeric values and cycles need special handling. Use explicit serialization rules for APIs and structuredClone for supported in-memory cloning.
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 are the limitations of JSON.stringify 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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