add original version of old crummy monitor

public/shared.js

@@ -0,0 +1,115 @@
+"use strict"
+
+/* global document, window */
+const location = document.location
+const performance = window.performance
+
+import config from "./config.js"
+
+export function isString(x) {
+  return typeof x === "string"
+}
+
+export function isEmpty(x) {
+  return (Array.isArray(x) ? x : Object.keys(x)).length === 0
+}
+
+export const q = (selector, root = document) => root.querySelector(selector)
+
+const _evlisteners = {}
+
+/**
+ * @param {String}   event   [description]
+ * @param {Function} cb      [description]
+ * @param {?{once: bool, target: Element = document}} options
+ */
+export function on(event, cb, options = {}) {
+  const target = options.target || document
+  if ((_evlisteners[target] ?? {})[event]) {
+    console.warn(`Replacing previous event listener for '${event}' on target:`, target)
+    off(event, target)
+  }
+  target.addEventListener(event, cb, { once: !!options.once })
+  if (!_evlisteners[target]) {
+    _evlisteners[target] = {}
+  }
+  _evlisteners[target][event] = cb
+}
+
+export function off(event, target = document) {
+  if (!_evlisteners[target] || !_evlisteners[target][event]) {
+    return
+  }
+  target.removeEventListener(event, _evlisteners[target][event])
+  delete _evlisteners[target][event]
+  if (isEmpty(_evlisteners[target])) {
+    delete _evlisteners[target]
+  }
+}
+
+export function node(type, { appendTo, cls, text, data, style, ...attrs } = {}) {
+  let elem = isString(type) ? document.createElement(type) : type
+  if (cls) {
+    if (isString(cls)) {
+      elem.className = cls
+    } else {
+      for (const [name, on] of Object.entries(cls)) {
+        if (on) {
+          elem.classList.add(name)
+        } else {
+          elem.classList.remove(name)
+        }
+      }
+    }
+  }
+  if (text) {
+    elem.textContent = text
+  }
+  Object.assign(elem.dataset, data ?? {})
+  Object.assign(elem.style, style ?? {})
+  for (const name in attrs) {
+    elem.setAttribute(name, attrs[name])
+  }
+  if (appendTo) {
+    elem = appendTo.appendChild(elem)
+  }
+  return elem
+}
+
+/**
+ * Some duration conversion constants.
+ */
+export const ms_ns = 1_000_000 // nanoseconds in a millisecond
+export const s_ms = 1_000 // milliseconds in a second
+export const s_ns = 1_000_000_000 // nanoseconds in a second
+
+export function session_url(sid) {
+  return `${config.wsurl}/${sid}`
+}
+
+export function session_id_from_url(url) {
+  const wsurl = new URL(config.wsurl)
+  const match = RegExp(`${wsurl.pathname}/([^/]+)$`).exec(url)
+  return !match ? null : match[1]
+}
+
+export function clear(container) {
+  while (container.children.length > 0) {
+    const child = container.children[0]
+    child.remove()
+  }
+}
+
+export function session_id() {
+  const match = /^#?(.+)/.exec(location.hash)
+  return match ? match[1] : null
+}
+
+/**
+ * Guess the exact current server time.
+ */
+export function servertime_now_ns() {
+  const now_ms = performance.now()
+  const delta_ns = ms_ns * (now_ms - toffset_ms)
+  return servertime + delta_ns
+}