Small Ideas That Solve Real Problems

Assigning objects creates references, causing accidental mutations.

Use Object.assign({}, obj) or spread {...obj} to create shallow copies.

Prevents mutation bugs and allows safe object manipulation.

Squaring numbers like 48 or 52 requires long multiplication.

Use (50-a)² = 2500 - 100a + a² or (50+a)² = 2500 + 100a + a²

Converts difficult squares into simple arithmetic around 2500.

Checking if any/all items meet a condition requires manual loops with break statements.

Use Array.some() to check if any item matches, Array.every() for all items.

More readable and stops execution early for better performance.

Testing divisibility by 4 for large numbers requires division.

Check only the last two digits. If they form a number divisible by 4, the whole number is.

Instantly test any number for divisibility by 4.

Flattening nested arrays requires recursive functions or complex reduce logic.

Use Array.flat(depth) to flatten arrays to specified depth in one line.

Eliminates 20+ lines of recursive flattening code.

Checking divisibility by 6 requires checking both 2 and 3 separately.

Number must be even AND sum of digits divisible by 3.

Combines two simple rules for quick divisibility check.

Sequential await calls waste time when operations could run in parallel.

Use Promise.all() to execute multiple async operations simultaneously.

Can reduce execution time by 70% for independent async operations.

Multiplying by 25 requires complex long multiplication.

Divide by 4 and multiply by 100 (or multiply by 100 and divide by 4).

Converts multiplication into simple division by 4.