function foo() {
    let p = new Promise(function(resolve, reject) {
        setTimeout(function() {
            console.log('foo');
            resolve('foo111');
        }, 1000);
    });
    return p;
}

function bar() {
    console.log('bar');
    return 'bar111';
}

function foobar(x) {
    console.log(x);
}

let out = foo()
.then(function() {
    return bar();
})
.then(function(x) {
    foobar(x);
});