Also in TypeScript 5.7 is a new compiler option, –rewriteRelativeImportExtensions. When an import path is relative and ends with a TypeScript extension (.ts, .tsx, .mts, .cts), and it is a non-declaration file, the compiler will rewrite the path to the corresponding JavaScript extension (.js, .jsx, .mjs, .cjs). This allows for writing TypeScript code that can be run in place and be compiled into JavaScript code when ready.
TypeScript 5.7 comes on the heels of the September release of TypeScript 5.6, with capabilities including disallowing nullish and truthy checks on syntax that never varies on nullishness or truthiness.
Other features in TypeScript 5.7 include the following: