Sequential code execution in angular/ typescript

Question

How can I make my code run sequentially? For example,

1. If I have a for loop which gets some data from a service, I want the n+1 iteration to run

Answer 1

You can do it with Promise.

someMethod() : Promise {

 return new Promise((resolve) => {
  for ( var i = 0; i < someLength; i++) {
        // get some data
        this.dataService.get(i).subscribe(data => {
            // do something with the data
        }); 

if(i==someLength-1){resolve();}
    }


}).then(()=>{ 


    // 
    console.log ('print me only after all iterations');

    // ....
    // some more lines of code
})
}