Tiny co shim

c.js

module.exports = function( fn, ...args ) {
  return new Promise( ( resolve, reject ) => {
    const it = fn.apply( this, args );
    const [ yay, boo ] = [ 'next', 'throw' ].map( factory );

    yay();

    function factory( method ) {
      return function( res ) {
        try {
          const { done, value } = it[ method ]( res );
          done ? resolve( value ) : value.then( yay, boo );
        } catch ( err ) {
          return reject( err );
        }
      }
    }
  });
};

index.js

const c = require('./lib/c');

const wait = n => new Promise( resolve => setTimeout( resolve, n ) );

c(function*() {
  let count = 0;
  while ( true ) {
    console.log( count++ );
    yield wait( 1000 );
  }
});