promises-callbacks-way.js

async1(function() {
  // do some stuff
  
  async2(function(inputsFromAsync1) {
    // do stuff that depends on inputsFromAsync1
    
    async3(function(inputsFromAsync2) {
      // do stuff that depends on inputsFromAsync2
      
      async4(function(inputsFromAsync3) {
        // more stuff that depends on inputsFromAsync3
        
        // finally execute func5() that should "in time"
        // get executed after all previous logic
        func5();
      });
    });
  });
});