@silverhand/mermaid-isomorphic
Version:
Transform mermaid diagrams in the browser or Node.js
188 lines (186 loc) • 6.35 kB
JavaScript
import { chromium } from 'playwright';
const html = `<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<script src="https://cdn.jsdelivr.net/npm/mermaid@11.4.1/dist/mermaid.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@6.7.1/css/all.css" />
</head>
</html>
`;
/* c8 ignore start */
/**
* Render mermaid diagrams in the browser.
*
* @param options
* The options used to render the diagrams
* @returns
* A settled promise that holds the rendering results.
*/
async function renderDiagrams({ diagrams, mermaidConfig, prefix, screenshot }) {
await Promise.all(Array.from(document.fonts, (font) => font.load()));
const parser = new DOMParser();
const serializer = new XMLSerializer();
mermaid.initialize(mermaidConfig);
/**
* Get an aria value form a referencing attribute.
*
* @param element
* The SVG element the get the value from.
* @param attribute
* The attribute whose value to get.
* @returns
* The aria value.
*/
// eslint-disable-next-line unicorn/consistent-function-scoping
function getAriaValue(element, attribute) {
const value = element.getAttribute(attribute);
if (!value) {
return;
}
let result = '';
for (const id of value.split(/\s+/)) {
const node = element.getElementById(id);
if (node) {
result += node.textContent;
}
}
return result;
}
return Promise.allSettled(diagrams.map(async (diagram, index) => {
const id = `${prefix}-${index}`;
try {
const { svg } = await mermaid.render(id, diagram);
const root = parser.parseFromString(svg, 'text/html');
const [element] = root.getElementsByTagName('svg');
const { height, width } = element.viewBox.baseVal;
const description = getAriaValue(element, 'aria-describedby');
const title = getAriaValue(element, 'aria-labelledby');
if (screenshot) {
document.body.append(element);
}
const result = {
height,
id,
svg: serializer.serializeToString(element),
width
};
if (description) {
result.description = description;
}
if (title) {
result.title = title;
}
return result;
}
catch (error) {
throw error instanceof Error
? { name: error.name, stack: error.stack, message: error.message }
: error;
}
}));
}
/**
* Launch a browser and a single browser context.
*
* @param browserType
* The browser type to launch.
* @param launchOptions
* Optional launch options
* @returns
* A simple browser context wrapper
*/
async function getBrowser(browserType, launchOptions) {
const browser = await (typeof launchOptions === 'string'
? browserType.connectOverCDP(launchOptions)
: browserType.launch(launchOptions));
const context = await browser.newContext({ bypassCSP: true });
return {
async close() {
await context.close();
await browser.close();
},
newPage() {
return context.newPage();
}
};
}
/**
* Create a Mermaid renderer.
*
* The Mermaid renderer manages a browser instance. If multiple diagrams are being rendered
* simultaneously, the internal browser instance will be re-used. If no diagrams are being rendered,
* the browser will be closed.
*
* @param options
* The options of the Mermaid renderer.
* @returns
* A function that renders Mermaid diagrams in the browser.
*/
export function createMermaidRenderer(options = {}) {
const { browserType = chromium, launchOptions } = options;
let browserPromise;
let count = 0;
return async (diagrams, renderOptions) => {
count += 1;
if (!browserPromise) {
browserPromise = getBrowser(browserType, launchOptions);
}
const context = await browserPromise;
let page;
let renderResults;
try {
page = await context.newPage();
await page.goto(`data:text/html,${encodeURIComponent(html)}`);
const promises = [];
const css = renderOptions?.css;
if (typeof css === 'string' || css instanceof URL) {
promises.push(page.addStyleTag({ url: String(css) }));
}
else if (css) {
for (const url of css) {
promises.push(page.addStyleTag({ url: String(url) }));
}
}
await Promise.all(promises);
renderResults = await page.evaluate(renderDiagrams, {
diagrams,
screenshot: Boolean(renderOptions?.screenshot),
mermaidConfig: {
fontFamily: 'arial,sans-serif',
...renderOptions?.mermaidConfig
},
prefix: renderOptions?.prefix ?? 'mermaid'
});
if (renderOptions?.screenshot) {
for (const result of renderResults) {
if (result.status === 'fulfilled') {
result.value.screenshot = await page
.locator(`#${result.value.id}`)
.screenshot({ omitBackground: true });
}
}
}
}
finally {
await page?.close();
count -= 1;
if (!count) {
browserPromise = undefined;
context.close();
}
}
for (const result of renderResults) {
if (result.status !== 'rejected') {
continue;
}
const { reason } = result;
if (reason && 'name' in reason && 'message' in reason && 'stack' in reason) {
Object.setPrototypeOf(reason, Error.prototype);
}
}
return renderResults;
};
}
//# sourceMappingURL=mermaid-isomorphic.js.map