From 9fd760ce75fd76716888997852ca85394eeab49a Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Mon, 20 Jan 2020 15:12:30 +0000
Subject: [PATCH] Add disable <textarea/> children flag (#17874)

---
 .../src/__tests__/ReactDOMTextarea-test.js    | 236 ++++++++++++------
 .../react-dom/src/client/ReactDOMTextarea.js  |  28 ++-
 packages/shared/ReactFeatureFlags.js          |   3 +
 .../forks/ReactFeatureFlags.native-fb.js      |   1 +
 .../forks/ReactFeatureFlags.native-oss.js     |   1 +
 .../forks/ReactFeatureFlags.persistent.js     |   1 +
 .../forks/ReactFeatureFlags.test-renderer.js  |   1 +
 .../ReactFeatureFlags.test-renderer.www.js    |   1 +
 .../shared/forks/ReactFeatureFlags.www.js     |   2 +
 9 files changed, 186 insertions(+), 88 deletions(-)

diff --git a/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js b/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
index ac40d1e230b7d..92d1142f5b186 100644
--- a/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
@@ -19,6 +19,8 @@ describe('ReactDOMTextarea', () => {
 
   let renderTextarea;
 
+  const ReactFeatureFlags = require('shared/ReactFeatureFlags');
+
   beforeEach(() => {
     jest.resetModules();
 
@@ -287,23 +289,58 @@ describe('ReactDOMTextarea', () => {
     }
   });
 
-  it('should treat children like `defaultValue`', () => {
-    const container = document.createElement('div');
-    let stub = <textarea>giraffe</textarea>;
-    let node;
+  if (ReactFeatureFlags.disableTextareaChildren) {
+    it('should ignore children content', () => {
+      const container = document.createElement('div');
+      let stub = <textarea>giraffe</textarea>;
+      let node;
 
-    expect(() => {
-      node = renderTextarea(stub, container);
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
+      expect(() => {
+        node = renderTextarea(stub, container);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('');
+      // Changing children should do nothing, it functions like `defaultValue`.
+      stub = ReactDOM.render(<textarea>gorilla</textarea>, container);
+      expect(node.value).toEqual('');
+    });
+  }
 
-    expect(node.value).toBe('giraffe');
+  if (ReactFeatureFlags.disableTextareaChildren) {
+    it('should receive defaultValue and still ignore children content', () => {
+      let node;
 
-    // Changing children should do nothing, it functions like `defaultValue`.
-    stub = ReactDOM.render(<textarea>gorilla</textarea>, container);
-    expect(node.value).toEqual('giraffe');
-  });
+      expect(() => {
+        node = renderTextarea(
+          <textarea defaultValue="dragon">monkey</textarea>,
+        );
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('dragon');
+    });
+  }
+
+  if (!ReactFeatureFlags.disableTextareaChildren) {
+    it('should treat children like `defaultValue`', () => {
+      const container = document.createElement('div');
+      let stub = <textarea>giraffe</textarea>;
+      let node;
+
+      expect(() => {
+        node = renderTextarea(stub, container);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+
+      expect(node.value).toBe('giraffe');
+
+      // Changing children should do nothing, it functions like `defaultValue`.
+      stub = ReactDOM.render(<textarea>gorilla</textarea>, container);
+      expect(node.value).toEqual('giraffe');
+    });
+  }
 
   it('should keep value when switching to uncontrolled element if not changed', () => {
     const container = document.createElement('div');
@@ -342,71 +379,120 @@ describe('ReactDOMTextarea', () => {
     expect(node.value).toEqual('puppies');
   });
 
-  it('should allow numbers as children', () => {
-    let node;
-    expect(() => {
-      node = renderTextarea(<textarea>{17}</textarea>);
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
-    expect(node.value).toBe('17');
-  });
-
-  it('should allow booleans as children', () => {
-    let node;
-    expect(() => {
-      node = renderTextarea(<textarea>{false}</textarea>);
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
-    expect(node.value).toBe('false');
-  });
-
-  it('should allow objects as children', () => {
-    const obj = {
-      toString: function() {
-        return 'sharkswithlasers';
-      },
-    };
-    let node;
-    expect(() => {
-      node = renderTextarea(<textarea>{obj}</textarea>);
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
-    expect(node.value).toBe('sharkswithlasers');
-  });
-
-  it('should throw with multiple or invalid children', () => {
-    expect(() => {
-      expect(() =>
-        ReactTestUtils.renderIntoDocument(
-          <textarea>
-            {'hello'}
-            {'there'}
-          </textarea>,
-        ),
-      ).toThrow('<textarea> can only have at most one child');
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
+  if (ReactFeatureFlags.disableTextareaChildren) {
+    it('should ignore numbers as children', () => {
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{17}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('');
+    });
+  }
+
+  if (!ReactFeatureFlags.disableTextareaChildren) {
+    it('should allow numbers as children', () => {
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{17}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('17');
+    });
+  }
+
+  if (ReactFeatureFlags.disableTextareaChildren) {
+    it('should ignore booleans as children', () => {
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{false}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('');
+    });
+  }
+
+  if (!ReactFeatureFlags.disableTextareaChildren) {
+    it('should allow booleans as children', () => {
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{false}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('false');
+    });
+  }
+
+  if (ReactFeatureFlags.disableTextareaChildren) {
+    it('should ignore objects as children', () => {
+      const obj = {
+        toString: function() {
+          return 'sharkswithlasers';
+        },
+      };
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{obj}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('');
+    });
+  }
+
+  if (!ReactFeatureFlags.disableTextareaChildren) {
+    it('should allow objects as children', () => {
+      const obj = {
+        toString: function() {
+          return 'sharkswithlasers';
+        },
+      };
+      let node;
+      expect(() => {
+        node = renderTextarea(<textarea>{obj}</textarea>);
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+      expect(node.value).toBe('sharkswithlasers');
+    });
+  }
 
-    let node;
-    expect(() => {
-      expect(
-        () =>
-          (node = renderTextarea(
+  if (!ReactFeatureFlags.disableTextareaChildren) {
+    it('should throw with multiple or invalid children', () => {
+      expect(() => {
+        expect(() =>
+          ReactTestUtils.renderIntoDocument(
             <textarea>
-              <strong />
+              {'hello'}
+              {'there'}
             </textarea>,
-          )),
-      ).not.toThrow();
-    }).toErrorDev(
-      'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
-    );
+          ),
+        ).toThrow('<textarea> can only have at most one child');
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
 
-    expect(node.value).toBe('[object Object]');
-  });
+      let node;
+      expect(() => {
+        expect(
+          () =>
+            (node = renderTextarea(
+              <textarea>
+                <strong />
+              </textarea>,
+            )),
+        ).not.toThrow();
+      }).toErrorDev(
+        'Use the `defaultValue` or `value` props instead of setting children on <textarea>.',
+      );
+
+      expect(node.value).toBe('[object Object]');
+    });
+  }
 
   it('should unmount', () => {
     const container = document.createElement('div');
diff --git a/packages/react-dom/src/client/ReactDOMTextarea.js b/packages/react-dom/src/client/ReactDOMTextarea.js
index dc436d1b552d7..9c1505bac6345 100644
--- a/packages/react-dom/src/client/ReactDOMTextarea.js
+++ b/packages/react-dom/src/client/ReactDOMTextarea.js
@@ -14,6 +14,8 @@ import {getCurrentFiberOwnerNameInDevOrNull} from 'react-reconciler/src/ReactCur
 import {getToStringValue, toString} from './ToStringValue';
 import type {ToStringValue} from './ToStringValue';
 
+import {disableTextareaChildren} from 'shared/ReactFeatureFlags';
+
 let didWarnValDefaultVal = false;
 
 type TextAreaWithWrapperState = HTMLTextAreaElement & {|
@@ -85,9 +87,7 @@ export function initWrapperState(element: Element, props: Object) {
 
   // Only bother fetching default value if we're going to use it
   if (initialValue == null) {
-    let defaultValue = props.defaultValue;
-    // TODO (yungsters): Remove support for children content in <textarea>.
-    let children = props.children;
+    let {children, defaultValue} = props;
     if (children != null) {
       if (__DEV__) {
         console.error(
@@ -95,19 +95,21 @@ export function initWrapperState(element: Element, props: Object) {
             'children on <textarea>.',
         );
       }
-      invariant(
-        defaultValue == null,
-        'If you supply `defaultValue` on a <textarea>, do not pass children.',
-      );
-      if (Array.isArray(children)) {
+      if (!disableTextareaChildren) {
         invariant(
-          children.length <= 1,
-          '<textarea> can only have at most one child.',
+          defaultValue == null,
+          'If you supply `defaultValue` on a <textarea>, do not pass children.',
         );
-        children = children[0];
+        if (Array.isArray(children)) {
+          invariant(
+            children.length <= 1,
+            '<textarea> can only have at most one child.',
+          );
+          children = children[0];
+        }
+
+        defaultValue = children;
       }
-
-      defaultValue = children;
     }
     if (defaultValue == null) {
       defaultValue = '';
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 62feacf3d48be..7a19c29ea8ae0 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -105,3 +105,6 @@ export const disableLegacyContext = false;
 
 // Disables React.createFactory
 export const disableCreateFactory = false;
+
+// Disables children for <textarea> elements
+export const disableTextareaChildren = false;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index 2c365a63e4a60..92790eb211824 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -46,6 +46,7 @@ export const disableSchedulerTimeoutBasedOnReactExpirationTime = false;
 export const enableTrainModelFix = false;
 export const enableTrustedTypesIntegration = false;
 export const disableCreateFactory = false;
+export const disableTextareaChildren = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index e1e4f6966f2c5..9facb94125d32 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -41,6 +41,7 @@ export const enableTrainModelFix = false;
 export const enableTrustedTypesIntegration = false;
 export const enableNativeTargetAsInstance = false;
 export const disableCreateFactory = false;
+export const disableTextareaChildren = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.persistent.js b/packages/shared/forks/ReactFeatureFlags.persistent.js
index a96660ce96d32..53547ef390bfc 100644
--- a/packages/shared/forks/ReactFeatureFlags.persistent.js
+++ b/packages/shared/forks/ReactFeatureFlags.persistent.js
@@ -41,6 +41,7 @@ export const enableTrainModelFix = false;
 export const enableTrustedTypesIntegration = false;
 export const enableNativeTargetAsInstance = false;
 export const disableCreateFactory = false;
+export const disableTextareaChildren = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 05bd491245d76..efb730ca7b542 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -41,6 +41,7 @@ export const enableTrainModelFix = false;
 export const enableTrustedTypesIntegration = false;
 export const enableNativeTargetAsInstance = false;
 export const disableCreateFactory = false;
+export const disableTextareaChildren = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index 18b6fa8438296..7fb5145ea723d 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -39,6 +39,7 @@ export const enableTrainModelFix = false;
 export const enableTrustedTypesIntegration = false;
 export const enableNativeTargetAsInstance = false;
 export const disableCreateFactory = false;
+export const disableTextareaChildren = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 871f868ed9a27..1abc4719ca262 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -92,6 +92,8 @@ export const enableNativeTargetAsInstance = false;
 
 export const disableCreateFactory = false;
 
+export const disableTextareaChildren = false;
+
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars
 type Check<_X, Y: _X, X: Y = _X> = null;