Load velocity only if motion is enabled

[maple3142]

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

velocity is added in site even if motion.enable is false

Issue Number(s): N/A

What is the new behavior?

velocity only added if motion.enable is true

• Screens with this changes: N/A
• Link to demo site with this changes: https://blog.maple3142.net/

How to use?

No need to change anything.

Does this PR introduce a breaking change?

• Yes.
• No.

[tsanie]

There is a problem, that the sidebar in Must/Mist is now hard-code dependent on the velocity. So need to refactor the motion.js first...

[maple3142]

Or change it to another option?
Like disable_velocity, and warn user about Must/Mist theme and motion depends on velocity.

[ivan-nginx]

No. i think no need to add extra options here, but about warn to Mist/Muse nice idea.
And as Tsanie talk above, need to refactor this somehow. To external repo maybe.

So, this will be merged? Let's wait another maintainers vision about this.

[wafer-li]

That is similar to the "turn off js" problem.

agree with @ivan-nginx
I think showing the warning is enough.

[sli1989]

So, add annotation in _config.yml?

[geekrainy]

To be confirmed

[geekrainy]

Caused by click button did not respond.

hexo-theme-next/source/js/src/utils.js

Line 113 in ca2554b

$('body').velocity('scroll');

[stevenjoezhang]

Superseded by #951