Check out example codes for "typescript create file and download". It will help you in understanding the concepts better.

Code Example 1

var fileContents = "Hello world!";
var filename = "hello.txt";
var filetype = "text/plain";

var a = document.createElement("a");
dataURI = "data:" + filetype +
    ";base64," + btoa(fileContents);
a.href = dataURI;
a['download'] = filename;
var e = document.createEvent("MouseEvents");
// Use of deprecated function to satisfy TypeScript.
e.initMouseEvent("click", true, false,
    document.defaultView, 0, 0, 0, 0, 0,
    false, false, false, false, 0, null);
a.dispatchEvent(e);
a.removeNode();

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