refactor($theme-default): toc

[shigma]

Summary

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
• Build-related changes
• Other, please describe:

If changing the UI of default theme, please provide the before/after screenshot:

Does this PR introduce a breaking change? (check one)

• Yes
• No

The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

You have tested in the following browsers: (Providing a detailed version will be better.)

• Chrome
• Firefox
• Safari
• Edge
• IE

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature
• Related documents have been updated
• Related tests have been updated

To avoid wasting your time, it's best to open a feature request issue first and wait for approval before working on it.

[ulivz]

Actually, I recommend that we separate the TOC plugin from the repo of vuepress, which is not our focus but will increase our additional maintenance costs.

[shigma]

Actually, I recommend that we separate the TOC plugin from the repo of vuepress, which is not our focus but will increase our additional maintenance costs.

I know, but some works need to be done to the VuePress core before TOC plugin can handle some issues.

[vue-bot]

Hey @shigma, thank you for your time and effort spent on this PR, contributions like yours help make Vue better for everyone. Cheers! 💚

[ulivz]

@shigma Reverted this commit since it caused another issue of rendering incorrect TOC: