DataviewJS for converting multiple tasks with 'project tags' into a mermaid flow chart

tasks_to_flowchart.js

/**

"Project tags" just means "any markdown task that that share a tag but separates the tasks 
identifier/position in the flow followed by the identifiers of the identifiers/positions of 
nodes with edges that point to this node.  In this way, the tags allow the tasks to remain 
sortable by their flow step identifier thusly:

#project/1 step 1 description
#project/2a/1 step 2a description
#project/2b/1 etc
#project/3/2a/2b etc etc.

Such that we get a flow (top down) that looks like:

    1
   / \
  2a  2b
   \ /
    3
    
*/

// Cribbed from StackOverflow. I am *so* not this good at regex.
function escapeRegex(s) {
	return s.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
}

const SOURCE = '!"Projects/Obsidian"';
const PR_TAG  = String(dv.pages('[[]]').pr_tag);
const PATTERN = new RegExp(escapeRegex("#" + PR_TAG + "/"));

let buffer = "";

function span(code) {
	buffer = buffer.concat(`${code}\n\n`);
}

span("```mermaid");
span("flowchart TD");

function extra_edges_from(tag) {
	var pr_tag = tag.text.split(' ')[0];
    	//dv.span(`- ${pr_tag}\n`);
	// +1 for leading # and +1 for trailing '/'
	var edges = pr_tag.substring(PR_TAG.length + 2).split("/");
    	//dv.span(`- Edges: ${edges}\n`);
	return edges;
}

function task_to_description_only(t) {
	var desc = "";
	// chop off project tag
	var parts = t.text.split(' ').slice(1);
	//dv.span(`- Desc No PR Tag: ${parts}`);
	// excise due, start, and scheduled dates
	parts = parts.filter(w => !w.match(/^[📅🛫⏳]\d{4}-\d{2}-\d{2}/));
	// excise date
	parts = parts.filter(w => !w.match(/\d{4}-\d{2}-\d{2}/));
	// excise priority
	parts = parts.filter(w => !w.match(/^[⏫🔼🔽]/));
	// excise inline annotations
	parts = parts.filter(w => !w.match(/^\[.*\]$/));
	parts = parts.map(w => {
	var m = w.match(/\[(.+)/) || w.match(/(.+)\]\(.+/);
	//dv.span(`\n\n${w}\n\n`);
	if (m) {
		//dv.span(`\n\nm[1]: ${m[1]}\n\n`);
		return m[1];
	} else {
		return w;
	}});
	desc = '"' + parts.join(' ') + '"';
	return desc;
}

function node_to_string(id, desc = "") {
	id = `id${id}`;
	if (desc.length > 0) {
		desc = `[${desc}]`;
	}
	return `${id}${desc}`;
}

function emit_root(id, desc) {
	span(node_to_string(id, desc));
}
function emit_branch(id, desc, src_id) {
	span(`${node_to_string(src_id)} --> ${node_to_string(id, desc)}`);
}

let tasks = dv.pages(SOURCE).file.tasks
	.where(t => t.text.match(PATTERN))
	.map(t => {
		//span(t.text);
		var edges = extra_edges_from(t);

		//span(`- Edges: ${edges}`);
		var dest = edges[0];
		var src_ids = edges.slice(1);		
		//span(`- src IDs: ${src_ids}`);
		var dest_desc = task_to_description_only(t);
		//span(`- desc: ${dest_desc}`);
		if (src_ids.length == 0) {
			emit_root(dest, dest_desc);
		} else {
			for(var i = 0; i < src_ids.length; i++) {
				emit_branch(dest, dest_desc, src_ids[i]);
			}
		}

		return t;
	});

span("```");
dv.span(buffer);

//dv.taskList(tasks, false);