Usage of async and await

function call(){
    console.log('call funtion');
    return new Promise(resolve=>{
        setTimeout(function(){
            console.log('call funtion timeout');
            resolve('dd');
        },1000);        
    });

}
function normalFunction() {
    console.log('normalFunction');
    return 'data'
}
// call(function(){
//     console.log('callback');
// });
async function asynctest() {
    console.log('start');
    await call();
    await normalFunction();
    await new Promise(resolve=>{ console.log('wait result'); resolve()});
    console.log('end');
}
asynctest();

Results of the

PS F:\zzj1026\Rnx\testEgg> node .\async.js
start
call funtion
call funtion timeout
normalFunction
wait result
end
PS F:\zzj1026\Rnx\testEgg>

Personal understanding of async means that this function is asynchronous. The keyword await is blocking (suspend the function and wait for the return result). If the return value is a promise, wait for the result of the resolve or reject of the promise. If it is the normal value returned by the function, directly Execute down

yield use

function call(){
    console.log('call funtion');
    return new Promise(resolve=>{
        setTimeout(function(){
            console.log('call funtion timeout');
            resolve('dd');
        },1000);        
    });

}
function normalFunction() {
    console.log('normalFunction');
    return 'data'
}
function* yieldFunc() {
    console.log('start');
    yield call();
    yield normalFunction();
    console.log('end');
}
let yieldData=yieldFunc();
let firstData=yieldData.next();
console.log(firstData);
firstData.value.then(function(data){
    console.log(data);
});
yieldData.next();
console.log(yieldData);

Results of the

PS F:\zzj1026\Rnx\testEgg> node .\async.js
start
call funtion
{ value: Promise { <pending> }, done: false }
normalFunction
{}
call funtion timeout
dd
PS F:\zzj1026\Rnx\testEgg>

Personal understanding: every time the function executes to yield, it returns a yield blocking value {value: Promise {}, done: false }, then the value can be processed, and then if done is true, it means that the function has been executed. Up