return-early-pattern

name	return-early-pattern
description	Apply the return early pattern with guard clauses to reduce nesting and improve readability. Use when refactoring conditional logic or writing new functions with precondition checks.

Use guard clauses to handle edge cases and failure conditions at the top of a function. Return immediately rather than nesting the happy path inside conditionals.

Good:

function process(data):
    if data is null: return
    if not data.is_valid(): return
    return do_work(data)

Bad:

function process(data):
    if data is not null:
        if data.is_valid():
            return do_work(data)

Apply this pattern where it genuinely makes the code cleaner — functions with clear precondition checks (null references, invalid parameters, boundary conditions) followed by main business logic as the happy path.

Only apply where it reduces complexity. Preserve simple if/else structures where they are already clear. Do not force the pattern into short functions where a single if/else is more readable, or when conditions represent legitimate alternative behaviors rather than failure cases.

References:

• https://en.wikipedia.org/wiki/Guard_(computer_science)
• https://medium.com/swlh/return-early-pattern-3d18a41bba8