promise based timeout

timeout.js

/* https://github.com/github/fetch/issues/175 */

function timeout(ms, promise) {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
      reject(new Error("timeout"))
    }, ms)
    promise.then(resolve, reject)
  })
}

/*Usage*/
timeout(1000, fetch('/hello')).then(function(response) {
  // process response
}).catch(function(error) {
  // might be a timeout error
})