Also, Microsoft has extended its deprecation of import assertion syntax (i.e. import ... assert {...}) to import() calls like import(..., { assert: {...}}). And DOM types have been updated to reflect the latest web standards, including some adjustments to Temporal APIs.
Other changes in TypeScript 6.0 include the RegExp.escape function for escaping regular expression characters such as *, ?, and +. Based on an ECMAScript proposal that has reached stage 4, RegExp.escape is now available in the es2025 library. Also, the contents of lib.dom.iterable.d.ts and lib.dom.asynciterable.d.ts are now included in lib.dom.d.ts. TypeScript’s lib option lets developers specify which global declarations a target runtime has.
Now feature-complete, TypeScript 6.0 also deprecates the asserts syntax. The asserts keyword was proposed to the JavaScript language via the import assertions proposal; however, the proposal eventually morphed into the import attributes proposal, which uses the with keyword instead of asserts.
