fetch 请求```bash fetchRequest (url, resolve, reject) { Promis

fetchRequest (url, resolve, reject) {
  Promise.race([
    fetch(url, {
      method: 'GET', headers: new  Headers({
        'Access-Control-Allow-Origin':'*',
        "Content-Type":'text/plain'
      }),
      mode: 'no-cors'
    }),
    new Promise(function (resolve, reject) {
      setTimeout(() => reject(new Error('request timeout')), 2000)
    })])
    .then((data) => {
      // console.log(data)
      // 请求成功
      resolve(data)
    }).catch((err) => {
    // console.log(err)
    // 请求失败
    reject(err)
  })
},