feat: prompt component (#16)

src/components/prompt/index.js

@@ -0,0 +1,10 @@
+import React from 'react';
+
+const Prompt = () => {
+  window.onbeforeunload = () => {
+    return true;
+  };
+  return <span style={{ display: 'none' }} />;
+};
+
+export default Prompt;

src/views/refund/refund.js

@@ -4,6 +4,7 @@ import injectSheet from 'react-jss';
 import { FaArrowRight } from 'react-icons/fa';
 import Background from '../../components/background';
 import StepsWizard from '../../components/stepswizard';
+import Prompt from '../../components/prompt';
 import View from '../../components/view';
 import { StepOne, StepTwo, StepFour } from './steps';
 
@@ -41,6 +42,7 @@ class Refund extends React.Component {
     const { classes, inRefundMode, goHome } = this.props;
     return (
       <Background>
+        <Prompt />
         <View className={classes.wrapper}>
           <StepsWizard
             dark={true}

src/views/swap/swap.js

@@ -6,6 +6,7 @@ import { generateKeys } from '../../action';
 import View from '../../components/view';
 import BackGround from '../../components/background';
 import StepsWizard from '../../components/stepswizard';
+import Prompt from '../../components/prompt';
 import { FEE } from '../../constants/fees';
 import { StepOne, StepTwo, StepThree, StepFour } from './steps';
 
@@ -51,6 +52,7 @@ const Swap = ({
 }) => {
   return (
     <BackGround>
+      <Prompt />
       <View className={classes.wrapper}>
         <StepsWizard
           range={4}