perf: improve performance

Author: chandq

src/clipboard.ts

@@ -40,7 +40,7 @@ export function fallbackCopyText(text: string, options?: CopyTextOptions): void
     container = document.body
   } = isNullish(options) ? {} : options;
 
-  const textEl = createFakeElement(text);
+  let textEl = createFakeElement(text);
   container.appendChild(textEl);
 
   select(textEl);
@@ -56,6 +56,8 @@ export function fallbackCopyText(text: string, options?: CopyTextOptions): void
     }
   } finally {
     container.removeChild(textEl);
+    // @ts-ignore
+    textEl = null;
     window.getSelection()?.removeAllRanges(); // 清除选区
   }
 }

src/download.ts

@@ -18,14 +18,16 @@ export function downloadURL(url: string, params?: LooseParams): void {
  * @param {Function} callback
  */
 export function downloadHref(href: string, filename: string, callback?: Function): void {
-  const eleLink = document.createElement('a');
+  let eleLink = document.createElement('a');
   eleLink.download = filename;
   eleLink.style.display = 'none';
   eleLink.href = href;
   document.body.appendChild(eleLink);
   eleLink.click();
   setTimeout(() => {
     document.body.removeChild(eleLink);
+    // @ts-ignore
+    eleLink = null;
     if (isFunction(callback)) {
       callback();
     }

src/file.ts

@@ -15,7 +15,7 @@ export function supportCanvas(): boolean {
  * @returns {HTMLInputElement}
  */
 export function chooseLocalFile(accept: string, changeCb: (FileList) => any): void {
-  const inputObj: HTMLInputElement = document.createElement('input');
+  let inputObj: HTMLInputElement = document.createElement('input');
   inputObj.setAttribute('id', String(Date.now()));
   inputObj.setAttribute('type', 'file');
   inputObj.setAttribute('style', 'visibility:hidden');
@@ -26,7 +26,12 @@ export function chooseLocalFile(accept: string, changeCb: (FileList) => any): vo
   inputObj.onchange = (e: PointerEvent): any => {
     changeCb((<HTMLInputElement>e.target).files);
 
-    setTimeout(() => document.body.removeChild(inputObj));
+    setTimeout(() => {
+      document.body.removeChild(inputObj);
+
+      // @ts-ignore
+      inputObj = null;
+    });
   };
 }
 

src/tooltip.ts

@@ -120,10 +120,12 @@ function mouseenter($customTitle: HTMLDivElement, title: string, e: PointerEvent
  * @returns {*}
  */
 function handleMouseLeave(rootContainer: HTMLElement | string = '#root'): void {
-  const rootEl = isString(rootContainer) ? document.querySelector(rootContainer) : rootContainer,
-    titleEl = document.querySelector('#customTitle1494304949567');
+  const rootEl = isString(rootContainer) ? document.querySelector(rootContainer) : rootContainer;
+  let titleEl = document.querySelector('#customTitle1494304949567');
   if (rootEl && titleEl) {
     rootEl.removeChild(titleEl);
+    // @ts-ignore
+    titleEl = null;
   }
 }
 const tooltipEvent = { handleMouseEnter, handleMouseLeave };

src/watermark.ts

@@ -83,7 +83,7 @@ export function genCanvasWM(content = '请勿外传', canvasWM?: ICanvasWM): voi
   const MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
   if (MutationObserver) {
     let mo: MutationObserver | null = new MutationObserver(function () {
-      const __wm: HTMLElement | null = document.querySelector(`#${watermarkId}`); // 只在__wm元素变动才重新调用 __canvasWM
+      let __wm: HTMLElement | null = document.querySelector(`#${watermarkId}`); // 只在__wm元素变动才重新调用 __canvasWM
       if (!__wm) {
         // 避免一直触发
         // console.log('regenerate watermark by delete::')
@@ -102,6 +102,9 @@ export function genCanvasWM(content = '请勿外传', canvasWM?: ICanvasWM): voi
           mo!.disconnect();
           mo = null;
           container.removeChild(__wm);
+
+          // @ts-ignore
+          __wm = null;
           genCanvasWM(content, canvasWM);
         }
       }