Combine throttle implementations (#7480)

panel/models/html.ts

@@ -6,6 +6,7 @@ import {entries} from "@bokehjs/core/util/object"
 import {Markup} from "@bokehjs/models/widgets/markup"
 import {PanelMarkupView} from "./layout"
 import {serializeEvent} from "./event-to-object"
+import {throttle} from "./util"
 
 import html_css from "styles/models/html.css"
 
@@ -79,29 +80,6 @@ export function run_scripts(node: Element): void {
   }
 }
 
-function throttle(func: Function, limit: number): any {
-  let lastFunc: ReturnType<typeof setTimeout> | undefined
-  let lastRan: number
-
-  return function(...args: any) {
-    // @ts-ignore
-    const context = this
-
-    if (!lastRan) {
-      func.apply(context, args)
-      lastRan = Date.now()
-    } else {
-      clearTimeout(lastFunc)
-      lastFunc = setTimeout(function() {
-        if ((Date.now() - lastRan) >= limit) {
-          func.apply(context, args)
-          lastRan = Date.now()
-        }
-      }, limit - (Date.now() - lastRan))
-    }
-  }
-}
-
 export class HTMLView extends PanelMarkupView {
   declare model: HTML
   _buffer: string | null = null

panel/models/util.ts

@@ -11,13 +11,27 @@ export const get = (obj: any, path: string, defaultValue: any = undefined) => {
   return result === undefined || result === obj ? defaultValue : result
 }
 
-export function throttle(func: any, timeFrame: number) {
-  let lastTime: number = 0
-  return function() {
-    const now: number = Number(new Date())
-    if (now - lastTime >= timeFrame) {
-      func()
-      lastTime = now
+export function throttle(func: Function, limit: number): any {
+  let lastRan: number = 0
+  let trailingCall: ReturnType<typeof setTimeout> | null = null
+
+  return function(...args: any) {
+    // @ts-ignore
+    const context = this
+    const now = Date.now()
+    if (trailingCall) {
+      clearTimeout(trailingCall)
+    }
+
+    if ((now - lastRan) >= limit) {
+      func.apply(context, args)
+      lastRan = Date.now()
+    } else {
+      trailingCall = setTimeout(function() {
+        func.apply(context, args)
+        lastRan = Date.now()
+        trailingCall = null
+      }, limit - (now - lastRan))
     }
   }
 }