将 javascript 函数与 promise 同步，socket.io 发出

Question

I'm building a web app and am trying to emit data to a server in a particular order, using socket.io's emit(). Basically, I'm trying to send two sets of data synchronously and then a "submit" message after both previous sets of data ( steps and files ) are completely sent. My problem is that the "submit" message is sent before the files has finished being sent. I'm trying to use Promises but it's not working, and I'm guessing there's a mistake with the usage.

sendToServer() {
    Promise.all([
        new Promise((res) => res(this.sendSteps())),
        new Promise((res) => res(this.sendFiles()))
    ]).then(this.sendSubmit());
}

Update:

I also tried this but it doesn't solve the problem. sendSubmit() still starts before sendFiles() is done.

async sendToServer() {
    return new Promise((res, rej) => res(this.sendSteps()))
        .then(() => {
            return new Promise((res, rej) => res(this.sendFiles()));
        })
        .then(() => {
            return new Promise((res, rej) => res(this.sendSubmit()));
        });
}

Answer 1

Please rewrite the code like this and let me know.

sendToServer() {
    Promise.all([
        new Promise((resolve, reject) => resolve(this.sendSteps())),
        new Promise((resolve, reject) => resolve(this.sendFiles()))
    ]).then(()=>{
        this.sendSubmit();
 });
}