Cannot execute all multiple child process with spawn

When I tried to run this following code to process multiple chile processes in order, I cannot run final process because before process keeps running. I am newbie of Linux and nodejs.

const childProcess = require('child_process');
function spawn (cmd,option){
return new Promise((resolve)=>{
    let p = childProcess.spawn(cmd,option);
    
    p.stdout.setEncoding('utf-8');
    p.stdout.on('data', (data)=>{
        console.log(data);
    });

    p.on('exit', (code)=>{
        console.log("process id:"+ p.pid + " child EXIT with code ")
        // console.log("process id:"+ p.pid + " child exited with code " + code)
        resolve();
    });

    p.stderr.on('data', (data)=>{
        console.log("process id:"+ p.pid + " child ERROR " + data)
        // console.log(data)
    });

})
}

async function nnmain(){
await spawn('ls');
await spawn('mkdir newtemp', {shell: true});
await spawn('df -h', {shell: true, stdio: 'inherit'});
await spawn('mkdir newtemp', {shell: true});
}
nnmain().catch(e=>console.log(e));