planning

node_modules/react-router/modules/Prompt.js

@@ -0,0 +1,52 @@
+import React from "react";
+import PropTypes from "prop-types";
+import invariant from "tiny-invariant";
+
+import Lifecycle from "./Lifecycle.js";
+import RouterContext from "./RouterContext.js";
+
+/**
+ * The public API for prompting the user before navigating away from a screen.
+ */
+function Prompt({ message, when = true }) {
+  return (
+    <RouterContext.Consumer>
+      {context => {
+        invariant(context, "You should not use <Prompt> outside a <Router>");
+
+        if (!when || context.staticContext) return null;
+
+        const method = context.history.block;
+
+        return (
+          <Lifecycle
+            onMount={self => {
+              self.release = method(message);
+            }}
+            onUpdate={(self, prevProps) => {
+              if (prevProps.message !== message) {
+                self.release();
+                self.release = method(message);
+              }
+            }}
+            onUnmount={self => {
+              self.release();
+            }}
+            message={message}
+          />
+        );
+      }}
+    </RouterContext.Consumer>
+  );
+}
+
+if (__DEV__) {
+  const messageType = PropTypes.oneOfType([PropTypes.func, PropTypes.string]);
+
+  Prompt.propTypes = {
+    when: PropTypes.bool,
+    message: messageType.isRequired
+  };
+}
+
+export default Prompt;