LowFile-scopeJavaScript / TypeScript Plug & play

Extract duplicated logic into functions

Duplicate sequences of statements must be extracted into a named function or utility.

Why this matters

Reduces maintenance cost and prevents logical drift.

Side-by-side examples engineers can pattern-match during review.

Avoid

total += item.price * item.qty; // repeated in multiple places

Prefer

const lineTotal=i=>i.price*i.qty; const total=items.reduce((a,i)=>a+lineTotal(i),0);

Bad

x.price*x.qty // repeated

Good

function lineTotal(i){ return i.price*i.qty }

From the same buckets as this rule.

Critical
Avoid Duplicating String Literals
Store repeated string literals in constants or variables to improve maintainability and reduce redundancy.
duplication-complexitymaintainability
Critical
Avoid Redundant `None` Comparisons
Identify cases where `x is None` or `x is not None` is used redundantly when `x` is always or never `None`. This may indicate a deeper logic issue.
duplication-complexityreadability-refactor+1
High
Avoid Functions That Always Return the Same Value
Identify functions that return the same value regardless of input. This may indicate poor design or a logic error.
duplication-complexityreadability-refactor+1