async与await实例

1. const doSomeThing = async () => {
   console.log(‘start do some thing’);
   await doA();
   await doB();
   console.log(‘do some thing done’);
   };

const doAnotherThing = () => {
console.log(‘do another thing’);
};

const doA = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
console.log(‘do a’);
resolve();
}, 10000);
});
};

const doB = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
console.log(‘do b’);
resolve();
}, 10000);
});
};
doSomeThing();
doAnotherThing();

所以async,await 的阻塞只在该函数作用域有效,本质上还是异步回调调用。

const doSomeThing = async () => {
console.log(‘start do some thing’);
await doA();
for (var i=0;i<10000;i++)
{
console.log(‘do’+i);
}

 console.log('do some thing done');

};

const doA = () => {
return new Promise((resolve, reject) => {
resolve();
});
};

const doAnotherThing = () => {
console.log(‘do another thing’);
};

doSomeThing();
doAnotherThing();

const doSomeThing = async () => {
console.log(‘start do some thing’);
for (var i=0;i<10000;i++)
{
console.log(‘do’+i);
}

await doA();

 console.log('do some thing done');

};

const doA = () => {
return new Promise((resolve, reject) => {
resolve();
});
};

const doAnotherThing = () => {
console.log(‘do another thing’);
};

doSomeThing();
doAnotherThing();

await 之后的函数和doAnotherThing();异步