Override markdown-it inline code and fence

custom_blocks.js

module.exports = function(md, options) {
    const blockIdMap = options.blockIdMap;
    const inlineIdMap = options.inlineIdMap;

    const oldFenceRule = md.renderer.rules.fence;
    const oldInlineCodeRule = md.renderer.rules.code_inline;
    
    md.renderer.rules.fence = function(tokens, idx, options, env, self) {
        const token = tokens[idx];
        const infoMatch = token.info.match(/^\s*\{([A-Za-z0-9]*)\}\s*/);
        if (infoMatch !== null && infoMatch.length === 2) { //infoMatch[0] is the whole thing, infoMatch[1] is the group
            const info = infoMatch[1];
            // if empty identifier, remove identifer and fallback to normal
            if (info.length === 0) {
                const skipLen = infoMatch[0].length;
                token.info = token.info.slice(skipLen);
                return oldFenceRule(tokens, idx, options, env, self);
            }
            // apply the func for this identifier
            const handler = blockIdMap[info];
            if (typeof handler === 'function') {
                return handler(token.content, tokens, idx, options, env, self);
            }
        }
    
        return oldFenceRule(tokens, idx, options, env, self);
    }
    
    md.renderer.rules.code_inline = function(tokens, idx, options, env, self) {
        const token = tokens[idx];
        const infoMatch = token.content.match(/^\s*\{([A-Za-z0-9]*)\}\s*/);
        if (infoMatch !== null && infoMatch.length === 2) { //infoMatch[0] is the whole thing, infoMatch[1] is the group 
            const skipLen = infoMatch[0].length;
            const info = infoMatch[1];
            // if empty identifier, remove identifer and fallback to normal
            if (info.length === 0) {
                token.content = token.content.slice(skipLen);
                return oldInlineCodeRule(tokens, idx, options, env, self);
            }
            // apply the func for this identifier
            const handler = inlineIdMap[info];
            if (typeof handler === 'function') {
                const content = token.content.slice(skipLen);
                return handler(content, tokens, idx, options, env, self);
            }
        }
    
        return oldInlineCodeRule(tokens, idx, options, env, self);
    }
}

index.js

const MarkdownIt = require('markdown-it');
const CustomBlocksPlugin = require('./custom_blocks');

const md = new MarkdownIt('commonmark');

let customBlocksOptions = {
    blockIdMap: {},
    inlineIdMap: {}
}
customBlocksOptions.blockIdMap.print = function(content) { return "IN BLOCK PRINT!"; };
customBlocksOptions.inlineIdMap.print = function(content) { return "IN INLINE PRINT!"; };

md.use(CustomBlocksPlugin, customBlocksOptions);

var result;
result = md.render('# hello!\npooper ```hello1```\n\n```\nhello2\ntest\n\n\ntesttest\n```\n\n');
console.log(result);
result = md.render('# hello!\npooper ```{} hello1```\n\n```{}  \nhello2\ntest\n\n\ntesttest\n```\n\n');
console.log(result);
result = md.render('# hello!\npooper ```{print} hello1```\n\n```{print}  \nhello2\ntest\n\n\ntesttest\n```\n\n');
console.log(result);