Destructuring in parameters
author: { name } reaches inside author. Its default { name: "unknown" } is used when author is missing, and the final = {} handles a call with no argument at all.
Destructuring pulls properties out of an object into variables in one line, with renaming, defaults and a rest object for whatever is left; spread ... copies one object's properties into a new one, which is how you merge objects.
Change the code and press Run (Ctrl+Enter). Predict what will happen first, then break it on purpose and read what changes. Your edits are saved and match the lesson page.
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Practice questions
Write the code in the editor, run it, then open the model answer to compare.
Given const movie = { title: "Lagaan", year: 2001, rating: null }, destructure title into name, year, and rating with a default of "not rated". Log all three and explain the rating.
Write withoutKeys(obj) that returns a copy of obj without createdAt and updatedAt, leaving the original unchanged.
Write updateEmail(user, email) that returns a new user with the new email, without changing user. Prove it by logging both.
Explain it without notes
Explain object destructuring with renaming and defaults, and when a default is used.
What's the difference between object rest and object spread?
Why is { ...obj } called a shallow copy, and what bug does that cause?
How does spread differ from Object.assign?
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Malgudi Days by R. K. Narayan, 256 pages
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