markdown2html/src/async-steps.ts

42 lines
1.2 KiB
TypeScript

// marked does not support asynchronous steps in the rendering process.
// as such, in order to support external renderers that do their processing
// async, this handles swapping out a placeholder for the additionally processed
// content after marked is finished rendering
let next_task_id = 1;
const data_binding = /{{@@!@!@@ MARKED ASYNC DATA BINDING PLACEHOLDER {{([0-9]+)}} @@!@!@@}}/g;
const pending_tasks: Record<number, Promise<string>> = { };
export function bind_data_async(data_generator: Promise<string>) {
const task_id = next_task_id++;
const placeholder = `{{@@!@!@@ MARKED ASYNC DATA BINDING PLACEHOLDER {{${task_id}}} @@!@!@@}}`;
pending_tasks[task_id] = data_generator;
return placeholder;
}
export async function resolve_async_bindings(html: string) {
const bindings: string[] = [ ];
const promises: Promise<string>[] = [ ];
let match: RegExpMatchArray;
while (match = data_binding.exec(html)) {
bindings.push(match[0]);
promises.push(pending_tasks[match[1]]);
delete pending_tasks[match[1]];
}
data_binding.lastIndex = 0;
const results = await Promise.all(promises);
for (let i = 0; i < results.length; i++) {
html = html.replace(bindings[i], results[i]);
}
return html;
}