The native FileReader API can be used to read a PDF and create a URL to its contents.
Data attributes allow you to store string data directly on HTML elements.
How to preview an image and check its dimensions and size before uploading.
You can prompt a download to begin in a user's browser without contacting a server.
Dates that are stored in Date objects can be compared or sorted via their Unix timestamp.
localStorage and sessionStorage objects allow you to store data from to user's browser.
The map() and forEach() methods both iterate through arrays, but are not interchangeable.