JavaScriptでリトライ

retry.js

const myFunc = () => {
  return new Promise((resolve, reject) => {
      if (Math.random() > 0.5) {
        console.log("resolve");
        resolve("OK");
      } else {
        console.log("reject");
        reject("Error");
      }
  })
}

function sleep(waitSeconds, func) {
  return new Promise(resolve => {
      setTimeout(() => {
        resolve(func())
      }, waitSeconds * 1000);
  })
}

function retry({retryCount=3, waitSeconds=1, func}) {
  let promise = Promise.reject().catch(() => func());
  for (let i = 0; i < retryCount; i++) {
    promise = promise.catch(err => {
      console.log("Retry:", i + 1);
      return sleep(waitSeconds, func)
    });
  }
  return promise;
}

retry({func: myFunc}).then(result => {
  console.log("success!", result);
}).catch(error => {
  console.log("failed!", error);
})