If all you want is to prevent them from copying and pasting into something else, you could store it in BSON instead of JSON. http://bsonspec.org/#/specification
Now that only OBFUSCATES it, and will not prevent a knowledgeable person from using it if they want to.
You could also encrypt it, but you still have a similar issue as you would be storing the decrypt key inside the javascript that loads the encrypted Json.
Anyone that really wants your data is going to be able to get it. Most browser have javascript debuggers that will let you extract, or view the data at runtime.
So it mostly comes down to how much effort you want to put into making your data difficult to get at. A significantly motivated person with get at your data no matter what you do.
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