an example promise function

Promise.js

/*
    To run this file:
    
        1. download this code or copy this code and put it in a file, with .js at the end of the filename
        2. in your command line go to the directory where the code is
        3. input in your command line: node Promise.js (or whatever your filename is called)
        4. SEE THE SECRET MESSAGE!!
*/

function myInnerPromise( value ) {

    return Promise.resolve( value + ' is ' );
}

function myInnerInnerPromise( value ) {

    return Promise.resolve( value + 'very cool.' );
}


/*
* @Promise
*/
function myPromise( x , y ) {

    if( !x || !y ) {

        return Promise.resolve( false );
    }

    // myInnerPromise returns the value z to the next inner 'then'
    return myInnerPromise( x + y )
        .then( function( z ) {

            // myInnerInnerPromise retuns w to the next inner 'then'
            return myInnerInnerPromise( z )
                .then( function( w ) {

                    /* 
                       this w is returned to the next outer 'then' 
                       because there are no more inner 'then's 
                    */
                    return w;
                });
        })
        .then( function( w ) {

            console.log( 'Final result:', w );
        })
        .catch( function( err ) {
            // this catch will catch any error that occurs within myInnerPromise

            console.log( 'Error:', err.message );
        });
}

myPromise( 'Taylor' , ' Swift' );