fix issues link references and prototypes

[Trott]

Marked version: 0.4.0

Markdown flavor: Markdown.pl

Description

Link with names that clashed with properties inherited from the
Object prototype (such as "constructor") were not expanding. This fixes
this issue.

Before this change, markdown of this form...:

Link: [constructor][].

[constructor]: https://example.org/

...resulted in HTML output of this form:

<p>Link: [constructor][].</p>

With this change, it now renders as expected:

<p>Link: <a href="https://example.org/">constructor</a>.</p>

Contributor

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• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

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• Draft GitHub release notes have been updated.
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• Merge PR

[UziTech]

@joshbruce @styfle
this may need to be polyfilled if we intend on supporting ie8

Object.create Browser Compatibility

[UziTech]

Can you keep the example numbers in order?

[Trott]

Sure, done. (I thought they were alphabetically ordered by section.)

[Trott]

this may need to be polyfilled if we intend on supporting ie8

The polyfill at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create does not support null as an argument. I suspect other polyfills may have the same shortcoming.

Would this be tolerable?

// IE8 does not have Object.create()
this.tokens.links = Object.create ? Object.create(null) || {};

The tiny edge-case bug this fixes will still exist in IE8, but it also means not having to ship a polyfill. An issue can be opened for adding the polyfill and it can happen later (or the issue can be closed whenever IE8 support is dropped).

EDIT: Also not sure if the tests are run in browsers. If so, we'll need a mechanism to skip the new test in IE8. Not familiar enough with the project to know offhand if one already exists...

[UziTech]

I'm ok with the check for Object.create, I'm also ok with not supporting IE8

[Trott]

I'm ok with the check for Object.create, I'm also ok with not supporting IE8

I'll assume "not support IE8" is the most likely path until someone else weighs in to the contrary. :-D

[joshbruce]

@styfle, @UziTech, et al: Given the data we have from #1215 and the fact that IE11 isn't supported by Microsoft anymore I'm pretty okay with not supporting IE8 as well.

Having said that, I do wonder what criteria we should set for supporting IE in general (more specifically JS engines)...feel like we almost had this conversation not too long ago.

[styfle]

@joshbruce There is some discussion of when to begin using newer JS features (namely ES6) in the following tickets:

• Coding standards #1089 - Coding standards
• Modularization of library #746 - Modularization of library

I am fine with dropping support for IE 8 but we have to be careful about IE 11 because that still has sizable market share in enterprise environments (unfortunately).