How to filter an array with Angular 2, 4 objects?

Question

JavaScript

Help me write a function that filters the first element in each of the "type"
objects from the json file and returns the second element of the object as an array with other objects, it will get the lines under the "title" variable (see the .json file).
I called this function getFilesbyType(type: string) , and I can't finish it.
Please help!
Thanks in advance!
ps json bullet via getItemsOfFiles(): Observable