promise（7）——使用await获取Promise对象的PromiseResult

1.await必须在async定义的方法中使用

let e = await 78910;
console.log(e);

2.当await右边为一个PromiseState为fulfilled的Promise对象时，则返回其PromiseResult值

async function main() {
  let p = new Promise((resolve, reject) => {
    resolve(156);
  });
  let result = await p;
  console.log(result);
  
  let p1 = new Promise((resolve, reject) => {
    reject(177);
  });
  try {
    let result1 = await p1;
  } catch (e) {
    console.log(e);
  }
}
main();

3.当await右边为为一个PromiseResult为rejected的Promise对象时，需要trycatch获取其PromiseResult

async function main() {
  let p = new Promise((resolve, reject) => {
    resolve(156);
  });
  let result = await p;
  console.log(result);
  
  let p1 = new Promise((resolve, reject) => {
    reject(177);
  });
  try {
    let result1 = await p1;
  } catch (e) {
    console.log(e);
  }
}
main();

4.如果await右边为一个非Promise对象，则直接返回右边内容

async function main() {
  let e = await 78910;
  console.log(e);
}
main();