v0.6.0

Additions

• Transformations - You can now add transformation markers to types and use the transform utility function to perform the transformations:

  function timestampToDate(ts: number) : Date {
      return new Date(ts);
  }
  
  function transformAge(age: number) : number {
      return age + 1;
  }
  
  type User = {
      username: string,
      createdAt: Transform<typeof timestampToDate>,
      age: string & Transform<["+$self", typeof transformAge]>
  }
  
  const myUser: User = {
      username: "GoogleFeud",
      createdAt: 1716657364400,
      age: "123"
  }
  
  console.log(transform<User>(myUser))
  
  // Transpiles to:
  let result_1;
  result_1 = {};
  result_1.createdAt = timestampToDate(myUser.createdAt);
  result_1.age = transformAge(+myUser.age);
  result_1.username = myUser.username;
  console.log(result_1);

• Undefined and Null types which can be used with conditional transformations and checks - null & Transform<...> is never, so these types need to exist.
• PostCheck utility type which can be used alongside Transform to perform validation of the transformed values.

Changes

• The playground now uses astro instead of next.js, and it's URL has been changed to googlefeud.github.io/ts-runtime-checks/playground. I'll be writing better and more interactive documentation over the next few weeks!
• You'll no longer see stringified typescript types inside errors, they've been made a lot more readable.
• Union type data now includes the possible variants in raw errors.
• You can now use unions with check types: (implements #40)

  function validate1(
    param: Assert<Min<10> & Max<30> | string & (StartsWith<"a"> | MinLen<3>) | number[] & MinLen<3>>
  ) {
    return true;
  }
  
  // Transpiles to:
  function validate1(param) {
      if ((typeof param !== "string" || !param.startsWith("a") && param.length < 3) && (typeof param !== "number" || param < 10 || param > 30))
          if (!Array.isArray(param) || param.length < 3)
              throw new Error("Expected param to be number, to be greater than 10 & to be less than 30 | string, to start with \"a\" or to have a length greater than 3 | array<number>, to have a length greater than 3");
          else {
              for (let i_1 = 0; i_1 < param.length; i_1++) {
                  if (typeof param[i_1] !== "number")
                      throw new Error("Expected param[" + i_1 + "] to be a number");
              }
          }
      return true;
  }

Breaking changes

• Removed the Or utility type - use the | operator.
• Changed the Eq utility type to be more flexible, its parameters have been reversed, and the type is now optional.