Cancelable async

cancelable.js

class Cancelable {
  constructor() {
    this.canceled = false
  }

  count(val) {
    return new Promise((resolve, reject) => {
      setTimeout(function() {
        resolve(val*val)
      }, 1000)
    })
  }

  async start() {
    for (const each of [1,2,3,4,5]) {
      if (this.canceled) {
        break
      }
      try {
        let answer = await this.count(each)
        console.log(each, answer)
      } catch(e) {
        console.log('Could not compute')
      }
    }
    console.log('done')
  }

  cancel() {
    this.canceled = true
  }
}

/*
  let foo = new Cancelable()
  foo.start()
  setTimeout(() => {
    foo.cancel()
  }, 5000)
*/