JavaScript

Migrating large JavaScript projects to TypeScript requires careful planning and resources. Attempting 100% perfect types from day one causes delays, while the overhead of compilation time, build steps, and complex configurations frustrates teams transitioning from pure JavaScript.

Pure JavaScript in large-scale backend systems allows functions to receive unexpected parameters without enforcement, leading to hidden bugs that are difficult to refactor safely. Consistency across large codebases with hundreds of thousands of lines becomes challenging without static typing.

TypeScript's type system provides a false sense of security. The transpiler cannot truly know type information due to JavaScript's dynamic nature, and empirical research shows TypeScript code contains equal or more bugs than JavaScript code, with longer bug fix times.

Building web applications with stateless HTTP protocol and client-side JavaScript requires complex synchronization between client state and server-side session stores for simple features like shopping carts, increasing development complexity.

Seemingly minor design adjustments often trigger extensive changes in the codebase, particularly when dealing with tightly coupled CSS or JavaScript frameworks.

JavaScript developers struggle with null/undefined reference errors when accessing properties on null or undefined values, resulting in unhelpful TypeError messages that are frustrating to debug.