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Array Sort

Q: Why does [1, 10, 2].sort() result in [1, 10, 2]?

Answer: Because sort() converts elements to strings before comparing. String '10' comes before '2'. You must provide a numeric compare function (a, b) => a - b..

Q: How do you reverse an array without changing the original?

Answer: Use the modern 'toReversed()' method, or copy it first: '[...arr].reverse()'..

Q: What is Fisher-Yates shuffle?

Answer: It is an efficient algorithm for shuffling an array randomly. While you can use sort(() => Math.random() - 0.5), it is not truly random and performs poorly compared to Fisher-Yates..

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Expert Answer & Key Takeaways

Mastering Array Sort is essential for high-fidelity technical architecture and senior engineering roles in 2026.

JavaScript Array Sort

Sorting is one of the most common operations in real-world apps. However, JavaScript's default sorting behavior is often misunderstood by beginners.

1. Default Sorting (Alphabetical)

The sort() method sorts an array alphabetically as strings. It mutates the original array.

const fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort(); // ["Apple", "Banana", "Mango", "Orange"]

2. Numeric Sort (Compare Function)

Because sort() treats values as strings, numbers like "25" will be greater than "100" because "2" comes after "1". To sort numbers, you must provide a Compare Function.

const points = [40, 100, 1, 5, 25, 10];
points.sort((a, b) => a - b); // Ascending: [1, 5, 10, 25, 40, 100]

3. Sorting Objects

Sorting lists of objects by a specific property is a daily task in frontend development.

const cars = [
  {type:"Volvo", year:2016},
  {type:"Saab", year:2001},
  {type:"BMW", year:2010}
];
cars.sort((a, b) => a.year - b.year);

4. toSorted() (Modern 2026 Standard)

The modern alternative toSorted() creates a new array instead of mutating the original. This is the preferred method in high-fidelity 2026 development.

const sorted = points.toSorted((a, b) => a - b);

[!CAUTION] Never use points.sort() on original state data (e.g., in React). Always use toSorted() or copy the array first using [...points].sort() to avoid side effects.

Array Sort

Expert Answer & Key Takeaways

JavaScript Array Sort

1. Default Sorting (Alphabetical)

2. Numeric Sort (Compare Function)

3. Sorting Objects

4. toSorted() (Modern 2026 Standard)

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Array Sort

Expert Answer & Key Takeaways

JavaScript Array Sort

1. Default Sorting (Alphabetical)

2. Numeric Sort (Compare Function)

3. Sorting Objects

4. toSorted() (Modern 2026 Standard)

Top Interview Questions

?Interview Question

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?Interview Question

Course4All Engineering Team

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