TypeScript 5.1 Beta 发布

TypeScript 5.1 发布了首个 Beta 测试版。

主要变化

更智能地检查未定义返回值的函数(undefined-Returning Functions)

 function foo() {     // no return }  // x = undefined let x = foo();

 //  fine - we inferred that 'f1' returns 'void' function f1() {     // no returns }  //  fine - 'void' doesn't need a return statement function f2(): void {     // no returns }  //  fine - 'any' doesn't need a return statement function f3(): any {     // no returns }  //  error! // A function whose declared type is neither 'void' nor 'any' must return a value. function f4(): undefined {     // no returns }

新代码

 //  Works in TypeScript 5.1! function f4(): undefined {     // no returns }  //  Works in TypeScript 5.1! takesFunction((): undefined => {     // no returns });

 //  Works in TypeScript 5.1! takesFunction(function f() {     //                 ^ return type is undefined      // no returns });  //  Works in TypeScript 5.1! takesFunction(function f() {     //                 ^ return type is undefined      return; });