types.ts

export const enum Job {
  FOO = "FOO",
  BAR = "BAR"
}

export const doJob = (job: Job) => {
  if(job == Job.FOO) {
    foo()
  }
  if(job == Job.BAR) {
    bar()
  }
}

// OR

export type SomeJob = "SOME_JOB";
export type AnotherJob = "ANOTHER_JOB";

export type Job = SomeJob | AnotherJob;

const doJob = (job:Job) => {
  if(job == "SOME_JOB") {
    ...
  }
   if(job == "ANOTHER_JOB") {
    ...
  }
}