Arrays & Array Methods
Arrays are ordered, zero-indexed, and dynamically sized. Mutating methods: push, pop, shift, unshift, splice, sort, reverse, fill. Non-mutating methods: concat, slice, join, flat, includes, indexOf, find, findIndex. Spread (...) copies or merges arrays. Destructuring extracts elements into variables. Arrays are objects — assignment copies the reference, not the values.
Practice Questions7
Q1. What is the output? ```js const arr = [1, 2, 3]; arr.push(4); console.log(arr.length); ```
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Q2. Which array method removes elements from an array and can insert new ones in their place?
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Q3. What is the output? ```js const a = [1, 2, 3]; const b = [...a, 4, 5]; console.log(b); ```
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Q4. What is the output? ```js const [first, , third] = [10, 20, 30]; console.log(first, third); ```
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Q5. Which of the following array methods do NOT mutate the original array? (More than one answer may be correct.)
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Q6. What is the output? ```js const nums = [3, 1, 2]; nums.sort(); console.log(nums); ```
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Q7. What does `[1, 2, 3].includes(2)` return?
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