Small Ideas That Solve Real Problems

Checking multiple OR conditions creates long, repetitive comparison chains.

Use Array.includes() to check if a value matches any item in an array of possibilities.

Reduces condition complexity by 70% and makes code more maintainable.

Multiplying numbers like 23×27 or 41×49 requires full multiplication.

When tens digit is same and ones add to 10: Multiply tens×(tens+1), then ones×ones.

Special case shortcut that saves 80% of calculation time.

Accessing deeply nested object properties requires multiple null/undefined checks.

Use optional chaining (?.) to safely access nested properties without explicit null checks.

Eliminates 90% of null checking code and prevents "Cannot read property" errors.

Adding fractions requires finding least common denominator which is time-consuming.

Use cross-multiplication: (a/b + c/d) = (ad + bc) / (bd)

Universal method that works for any fraction addition without finding LCD.

Using filter() to find a single item processes the entire array unnecessarily.

Use Array.find() which stops at the first match, improving performance.

Up to 100x faster for large arrays and makes intent clearer.

Multiplying by 99 requires long multiplication with carrying.

Multiply by 100 and subtract the original number.

Converts difficult multiplication into simple subtraction.

Removing duplicates from arrays requires nested loops or complex filter logic.

Convert array to Set (which only stores unique values) then back to array.

One-line solution that is 50x faster than traditional approaches.

Calculating 15% or 20% tips at restaurants requires mental math under pressure.

10% = move decimal left. 20% = double that. 15% = 10% + half of 10%.

Calculate common tip percentages in 3 seconds without calculator.