Check out example codes for "how to set a var in js to be a download". It will help you in understanding the concepts better.
Code Example 1
var textToSave = 'this is a test';
var hiddenElement = document.createElement('a');
hiddenElement.href = 'data:attachment/text,' + encodeURI(textToSave);
hiddenElement.target = '_blank';
hiddenElement.download = 'myFile.txt';
hiddenElement.click();
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