Support marked custom extensions

[mhamern]

I would like to propose a new feature that would support marked custom extensions. See marked docs.

Custom extensions can be used to define own rules (and renderer and tokenizer) for compiling markdown to html. Its useful for example for supporting tagging (like @ here on Github).

I tried to implement it in my local fork because I need it for something I'm wokin on, so I think I should be able to provide a PR.

However, there are some issues with my implementation, that I would like to discuss first.

1. we need to extend MarkedOptions class by extensions attribute. The problem here is that marked does not export the MarkedExtension so we have to either use any, provide own type, or create an issue in marked repo to export this interface.

2. We need to make some changes in MarkdownService because of the implementation of marked. In constructor and setter of options we need to pass the extensions to marked, like this marked.use({extensions: this.options.extensions}). In order to work correctly though we need to change the compile method in MarkdownService. Calling marked with options, as its done now, breaks the extensions. I debugged the marked code and found out, that after calling use, the extensions are processed by marked and its structure is changed a bit (renderer and tokenizer attributes are replace with renderers and tokenizers). Passing options directly to compile overrides the internal structure and extension renderers and tokenizers are not picked up by marked. I think, it would be better to call marked.setOptions (and marked.use if extensions are provided) in options setter and constructor and in compile method, just call marked without options.

As I said, this feature is important to me and I already made it work for my own use case, so I will gladly put a PR for it. @jfcere Whats your idea on the issues mentioned in points 1 and 2? Thanks

[Arxero]

I was just looking for this option (for mention people) if possible, and google brought me here, kind of stumped that it is not possible, looking forward to seeing this implemented.

[mike-pisman]

Hi, I am also want to create some custom extensions for my project. Any updates on this?
@mhamern could you elaborate how managed to implement it for your project?

[mhamern]

@mike-pisman Hi, after no response to my issue, I implemented my own very lightweight component and service.

As for questions asked in the issue

1. I defined my own MarkedOptions class with attribute extensions of type Array<TokenizerExtension | RendererExtension | (TokenizerExtension & RendererExtension)> | undefined

2. I implemented service where providing marked options (in constructor or by method call) calls marked.use(options) and in compile method, marked is called without the options marked(markdow).

[mike-pisman]

@mike-pisman Hi, after no response to my issue, I implemented my own very lightweight component and service.

As for questions asked in the issue

1. I defined my own `MarkedOptions` class with attribute extensions of type `Array<TokenizerExtension | RendererExtension | (TokenizerExtension & RendererExtension)> | undefined`

2. I implemented service where providing marked options (in constructor or by method call) calls `marked.use(options)` and in `compile` method, marked is called without the options `marked(markdow)`.

Thank you I will try to do the same

[jfcere]

The update to marked v9 has been completed as part of the ngx-markdown v17.0.0 release and includes the support for marked extensions.

Please make sure to read the release notes as there are breaking changes.