Difference between Sequential and Parallel executing in $q

In both of at the time of execution of an asynchronic operation only.

• But how the $q handle for this is a Sequential call or Parallel call on runtime?
• and let me brief explanation about the Difference between Sequential and Parallel executing in angular $q

Parallel Execution is something in which it doesn't wait for the previous process to be done,and Sequential is something in which process are executed one after another.

$q service is used for asynchronous call (parallel execution | promise handling),by default it does parallel execution,it does not have support for sequential execution. If you want a sequential execution you have to handle it manually, wheich means after getting response from one call you make another call.

var promise;
promise.then(fun(){
   var promise;
   promise.then(fun(){
   })
})