From 54c43180161c3c512e4698e7f2e85ce3c6f0ab50 Mon Sep 17 00:00:00 2001
From: Ron0115 <jayguess@qq.com>
Date: Thu, 16 Sep 2021 04:56:50 +0800
Subject: [PATCH] feat: add threshold to Page.isIntersectingViewport (#6497)

---
 docs/api.md                       |  7 ++++---
 src/common/JSHandle.ts            | 25 +++++++++++++------------
 test/assets/offscreenbuttons.html |  2 ++
 test/elementhandle.spec.ts        | 26 ++++++++++++++++++++++++++
 4 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/docs/api.md b/docs/api.md
index 9edfecd6b67..c996ff7c53c 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -322,7 +322,7 @@
   * [elementHandle.getProperties()](#elementhandlegetproperties)
   * [elementHandle.getProperty(propertyName)](#elementhandlegetpropertypropertyname)
   * [elementHandle.hover()](#elementhandlehover)
-  * [elementHandle.isIntersectingViewport()](#elementhandleisintersectingviewport)
+  * [elementHandle.isIntersectingViewport([options])](#elementhandleisintersectingviewportoptions)
   * [elementHandle.jsonValue()](#elementhandlejsonvalue)
   * [elementHandle.press(key[, options])](#elementhandlepresskey-options)
   * [elementHandle.screenshot([options])](#elementhandlescreenshotoptions)
@@ -4574,8 +4574,9 @@ Fetches a single property from the objectHandle.
 This method scrolls element into view if needed, and then uses [page.mouse](#pagemouse) to hover over the center of the element.
 If the element is detached from DOM, the method throws an error.
 
-#### elementHandle.isIntersectingViewport()
-
+#### elementHandle.isIntersectingViewport([options])
+- `options` <[Object]>
+  - `threshold` <[number]> threshold for the intersection between 0 (no intersection) and 1 (full intersection). Defaults to 1.
 - returns: <[Promise]<[boolean]>> Resolves to true if the element is visible in the current viewport.
 
 #### elementHandle.jsonValue()
diff --git a/src/common/JSHandle.ts b/src/common/JSHandle.ts
index adeb960576c..2e138c514e8 100644
--- a/src/common/JSHandle.ts
+++ b/src/common/JSHandle.ts
@@ -994,19 +994,20 @@ export class ElementHandle<
   /**
    * Resolves to true if the element is visible in the current viewport.
    */
-  async isIntersectingViewport(): Promise<boolean> {
-    return await this.evaluate<(element: Element) => Promise<boolean>>(
-      async (element) => {
-        const visibleRatio = await new Promise((resolve) => {
-          const observer = new IntersectionObserver((entries) => {
-            resolve(entries[0].intersectionRatio);
-            observer.disconnect();
-          });
-          observer.observe(element);
+  async isIntersectingViewport(options?: {
+    threshold?: number;
+  }): Promise<boolean> {
+    const { threshold = 0 } = options || {};
+    return await this.evaluate(async (element: Element, threshold: number) => {
+      const visibleRatio = await new Promise<number>((resolve) => {
+        const observer = new IntersectionObserver((entries) => {
+          resolve(entries[0].intersectionRatio);
+          observer.disconnect();
         });
-        return visibleRatio > 0;
-      }
-    );
+        observer.observe(element);
+      });
+      return threshold === 1 ? visibleRatio === 1 : visibleRatio > threshold;
+    }, threshold);
   }
 }
 
diff --git a/test/assets/offscreenbuttons.html b/test/assets/offscreenbuttons.html
index 005d465cbd9..e487caf4d35 100644
--- a/test/assets/offscreenbuttons.html
+++ b/test/assets/offscreenbuttons.html
@@ -17,6 +17,7 @@
   #btn8 { right: -80px; top: 200px; }
   #btn9 { right: -90px; top: 225px; }
   #btn10 { right: -100px; top: 250px; }
+  #btn11 { right: -99.999px; top: 275px; }
 </style>
 <button id=btn0>0</button>
 <button id=btn1>1</button>
@@ -29,6 +30,7 @@
 <button id=btn8>8</button>
 <button id=btn9>9</button>
 <button id=btn10>10</button>
+<button id=btn11>11</button>
 <script>
   for (const button of document.querySelectorAll('button')) {
     button.addEventListener('click', () => {
diff --git a/test/elementhandle.spec.ts b/test/elementhandle.spec.ts
index 8eeba003f0d..fc69daece11 100644
--- a/test/elementhandle.spec.ts
+++ b/test/elementhandle.spec.ts
@@ -282,6 +282,32 @@ describe('ElementHandle specs', function () {
         expect(await button.isIntersectingViewport()).toBe(visible);
       }
     });
+    it('should work with threshold', async () => {
+      const { page, server } = getTestState();
+
+      await page.goto(server.PREFIX + '/offscreenbuttons.html');
+      // a button almost cannot be seen
+      // sometimes we expect to return false by isIntersectingViewport1
+      const button = await page.$('#btn11');
+      expect(
+        await button.isIntersectingViewport({
+          threshold: 0.001,
+        })
+      ).toBe(false);
+    });
+    it('should work with threshold of 1', async () => {
+      const { page, server } = getTestState();
+
+      await page.goto(server.PREFIX + '/offscreenbuttons.html');
+      // a button almost cannot be seen
+      // sometimes we expect to return false by isIntersectingViewport1
+      const button = await page.$('#btn0');
+      expect(
+        await button.isIntersectingViewport({
+          threshold: 1,
+        })
+      ).toBe(true);
+    });
   });
 
   describe('Custom queries', function () {