Change the priorities of defaultChecked and checked

docs/examples/simple.jsx

@@ -130,6 +130,33 @@ export default class SimpleDemo extends React.Component {
           </p>
         </div>
 
+        <div>
+          <p>
+            <label>
+              <Checkbox
+                defaultChecked
+                checked={undefined}
+                onChange={onChange}
+                disabled={this.state.disabled}
+              />
+              &nbsp; defaultChecked rc-checkbox when checked value is undefined or null
+            </label>
+            &nbsp;&nbsp;
+          </p>
+          <p>
+            <label>
+              <input
+                type="checkbox"
+                defaultChecked
+                checked={undefined}
+                disabled={this.state.disabled}
+              />
+              &nbsp; defaultChecked native checkbox when checked value is undefined or null 
+            </label>
+            &nbsp;&nbsp;
+          </p>
+        </div>
+
         <button type="button" onClick={this.toggle}>
           toggle disabled
         </button>

src/index.jsx

@@ -1,4 +1,3 @@
-// eslint-disable-next-line import/no-extraneous-dependencies
 import React, { Component } from 'react';
 import classNames from 'classnames';
 
@@ -21,15 +20,18 @@ class Checkbox extends Component {
   constructor(props) {
     super(props);
 
-    const checked = 'checked' in props ? props.checked : props.defaultChecked;
+    const checked =
+      'checked' in props && !(props.checked === undefined || props.checked === null)
+        ? props.checked
+        : props.defaultChecked;
 
     this.state = {
       checked,
     };
   }
 
   static getDerivedStateFromProps(props, state) {
-    if ('checked' in props) {
+    if ('checked' in props && !(props.checked === undefined || props.checked === null)) {
       return {
         ...state,
         checked: props.checked,
@@ -46,12 +48,15 @@ class Checkbox extends Component {
     this.input.blur();
   }
 
-  handleChange = e => {
-    const { disabled, onChange } = this.props;
+  handleChange = (e) => {
+    const { disabled, onChange, checked } = this.props;
     if (disabled) {
       return;
     }
-    if (!('checked' in this.props)) {
+    if (
+      !('checked' in this.props) ||
+      ('checked' in this.props && (checked === undefined || checked === null))
+    ) {
       this.setState({
         checked: e.target.checked,
       });
@@ -73,7 +78,7 @@ class Checkbox extends Component {
     }
   };
 
-  saveInput = node => {
+  saveInput = (node) => {
     this.input = node;
   };