Promises

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

In Javscrtipt Promises, "mark as successful" is called resolve(), and "mark as failed" is called reject(). If you needed to create one manually, it would look like:

let myPromise = new Promise((resolve, reject) => {
  try {
    result = somethingLongSlowAndFlaky()
    if is_valid(result) { resolve() }
    else { reject() }
  }
  catch(error) {
    console.log(error)
    reject()
  }    
})