docs: Update Examples with Blockstore

[pinheadmz]

Chain requires Blockstore!

All scripts in docs/Examples updated and tested.

[codecov-io]

Codecov Report

Merging #832 into master will not change coverage.
The diff coverage is n/a.

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##           master     #832   +/-   ##
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  Coverage   62.09%   62.09%           
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  Files         147      147           
  Lines       25392    25392           
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  Hits        15766    15766           
  Misses       9626     9626

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[braydonf]

I don't think examples should recommend to use LevelBlockStore, as this wouldn't be a realistic use case. I could eventually see it being deprecated, see the charts on the PR #703.

Also these examples are highly likely to break without there being tests for them. I don't think it makes sense, or time efficient, to manually run each of these every time to verify they are working, so maintenance of them is problematic.

[pinheadmz]

@braydonf I couldnt figure out how to get a in-memory blockstore without directly calling LevelBlockStore. Because there's nothing like new Blockstore({memory: true})

Even Blockstore.create({memory: true}) will throw if location isn't specified... which is kinda the point of memory: true

[braydonf]

I think the recommended usage would actually be to save to disk. If you're writing an application, you'll be doing that.

[tynes]

I think the recommended usage would actually be to save to disk. If you're writing an application, you'll be doing that.

I don't think this is true in all cases. This is assuming you are syncing all of the blocks. SPV can work fully in memory. You can also have application logic that keeps a rolling buffer of blocks - as new ones come in, delete old ones.

Edit: SPV is not relevant here, as the headers are stored in the chaindb and not blockstore

[pinheadmz]

All of the examples so far run in memory, I was just aiming for consistency. Personally I don't like little demos like this leaving files around my computer.

[pinheadmz]

Also worth linking to this recent issue. Although this PR is not the solution, that's why I ran these!

[pinheadmz]

Closed by #846