Posts tagged “strict mode”

Master TypeScript 6.0's enhanced `--checkJs` to incrementally enforce strict mode on JavaScript files without breaking CI or forcing a big-bang migration.

TypeScript's strict mode catches most type errors, but `this` binding bugs still slip through. Learn how explicit `this` parameter annotations prevent runtime context loss that noImplicitThis alone cannot detect.

TypeScript 6.0 makes strictFunctionTypes the default, breaking callbacks that relied on bivariant parameter checking. Learn why contravariance matters and how to migrate production code without sacrificing type safety.

Most runtime property access errors stem from index signatures pretending to guarantee properties they don't. This flag exposes the lie and forces honest API contracts.

Most production TypeScript bugs stem from a single assumption: that strict mode catches every type safety hole. It doesn't. The exactOptionalPropertyTypes flag exposes runtime crashes that strict mode silently permits—here's why teams overlook it and how to fix it.

Most generic type bugs stem from variance issues that strict mode doesn't catch. TypeScript's new 'in' and 'out' annotations finally give developers explicit control over covariance and contravariance in generic parameters.

The engineering playbook for migrating production TypeScript codebases to TS 6.0 strict defaults—without breaking your build or losing velocity.

TypeScript 6.0 ships with strict mode enabled by default, drops ES5 support, and changes module resolution. Here's how to migrate production codebases without breaking CI pipelines.