send synchrouns request angular 6 [closed]

Answer 1

What you need is a

concatMap does not subscribe to the next observable until the previous completes,

from([your source array])
    .pipe(
        concatMap(
            (item in your array) => {
                return this.getPLateInfo.getInfoPlate(....
            }
        )
    )
    .subscribe(
        (received data from your api call) => {
            process received data here...
        }
    );

import them from:

import { from } from 'rxjs';
import { concatMap } from 'rxjs/operators';

More info on concatMap here.

EDIT:

Here is a working stackblitz

Your original "plateInfo" function will make more than 1000 api calls, I hope you know what you are doing.

Anyway, I had to limit the number of items in the array to keep stackblitz site responsive.

Answer 2

Try using await/async

async getResult(): MyCustomObject {
    if (typeof this.result === 'undefined') 
    {
        // save result
        this.result = await this.service.call()
        .toPromise()
        .then(resp =>resp as MyCustomObject);//Do you own cast here

    }
    return this.result;
}