feat: remove old code and lodash

package.json

@@ -34,7 +34,6 @@
   "author": "Hank Hsiao <hankxiao@yahoo-inc.com>",
   "dependencies": {
     "eventemitter3": "^5.0.0",
-    "lodash": "^4.17.15",
     "raf": "^3.0.0"
   },
   "devDependencies": {
@@ -79,5 +78,6 @@
   "prettier": {
     "singleQuote": true,
     "tabWidth": 4
-  }
+  },
+  "browserslist": "> 0.25%, not dead"
 }

src/lib/listen.js

@@ -3,7 +3,6 @@
  * Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
  */
 
-import assign from 'lodash/assign';
 import globalVars from '../globalVars';
 
 const { supportPassiveEvent } = globalVars;
@@ -29,7 +28,7 @@ function listen(target, eventType, handler, options) {
     let type = eventType;
 
     const eventOptions = supportPassiveEvent
-        ? assign({}, defaultEventOption, options)
+        ? Object.assign({}, defaultEventOption, options)
         : false;
 
     if (!target.addEventListener && target.attachEvent) {

src/mainEventConnectors.js

@@ -3,13 +3,8 @@
  * Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
  */
 
-import clone from 'lodash/clone';
-import throttle from 'lodash/throttle';
-import noop from 'lodash/noop';
-
 import AugmentedEvent from './AugmentedEvent';
 import globalVars from './globalVars';
-import leIE8 from './lib/leIE8';
 import listen from './lib/listen';
 import rAFThrottle from './lib/rAFThrottle';
 
@@ -34,6 +29,19 @@ function getHash(domNode) {
     return domNode.id || `target-id-${hashId++}`; // eslint-disable-line
 }
 
+function noop() {}
+
+function throttle(func, wait) {
+    let lastCall = 0;
+    return function (...args) {
+        const now = Date.now();
+        if (now - lastCall >= wait) {
+            lastCall = now;
+            func.apply(this, args);
+        }
+    };
+}
+
 /**
  * Connect a throttled event to a throttled main event, and return an event remover.
  * The number of connections to a throttled main event will be kept. If all throttled events
@@ -147,17 +155,10 @@ function connectContinuousEvent(target, mainEvent, event) {
 
             ae.main.update(e);
             EE.emit(throttledMainEvent, e, ae.main);
-            if (!leIE8) {
-                timer = setTimeout(
-                    endCallback.bind(null, e),
-                    throttleRate + EVENT_END_DELAY,
-                );
-            } else {
-                // For browser less then and equal to IE8, event object need to be cloned for setTimeout.
-                timer = setTimeout(() => {
-                    endCallback(clone(e));
-                }, throttleRate + EVENT_END_DELAY);
-            }
+            timer = setTimeout(
+                endCallback.bind(null, e),
+                throttleRate + EVENT_END_DELAY,
+            );
         }
 
         listeners[throttledMainEvent] = listen(

src/subscribe.js

@@ -4,7 +4,6 @@
  */
 
 import globalVars from './globalVars';
-import leIE8 from './lib/leIE8'; // less then or equal to IE8
 import mainEventConnectors from './mainEventConnectors';
 
 // constants
@@ -34,12 +33,6 @@ function subscribe(type, cb, options = {}) {
         throttleRate = 'raf';
     }
 
-    // turn off throttle if the browser is IE8 or less, because window.event will be reset
-    // when using any delayed function, i.g., setTimeout, or rAF.
-    if (leIE8) {
-        throttleRate = 0;
-    }
-
     // once those variables enabled, then never disabled.
     globalVars.enableScrollInfo =
         globalVars.enableScrollInfo || options.enableScrollInfo || false;