Template Method pattern



JavaScript Dev

In the Template method pattern, we break algorithms into small methods. There can be a scenario where data may need to be processed differently.

We may need to have some level of flexibility so that we can add new data processor in the future without any changes and in such a scenario Template method pattern comes in handy. It helps us to abstract or default specific parts which can vary as per processor. For example, Our app can read the file of any type like CSV, pdf, or doc but here data extract part can be different for each file, and after extraction of data, the remaining steps can be the same for the file because, in the end, it is just data. To abstract data extraction part we can go with the Template method pattern.


abstract class Main {
mine() {
// This method will go somewhere and find url
const fileLink = this.resolveFile(url);
// This method is abstract
// and sub class must implement their own parsing logic
const parsedData = this.parseData(fileLink);
// After parsing of files we will extract birth information
const extractedBorthday = this.extractBirthData(parsedData);
resolveUrl(url: string) {
// ... implmentation
extractBirthData(data:string) {
// ... implementation
class MainA extends Main {
pareData(link: string) {
return link.split(' - ').join(',')
const mainA = new MainA();

UML Class Diagram

System design of notification architecture

Source: Dive into design patterns