SOURCE

        var p2=new Promise(function(resolve,reject){
            console.log('p2 executing')
            resolve('p2 resolve')
        });
        var p3=new Promise(function(resolve,reject){
            console.log('p3 executing')
            resolve('p3 resolve')
        });
        var p1=new Promise(function(resolve,reject){
            console.log('p1 executing')
            resolve(p3)
        });
        p1.then(function(v){
            console.log(v)
        })
        p2.then(function(v){
            console.log(v)
        })