StickyBackToTop

src/components/AccountPage/index.js

@@ -34,6 +34,7 @@ import Button from 'components/base/Button'
 import FormattedVal from 'components/base/FormattedVal'
 import PillsDaysCount from 'components/PillsDaysCount'
 import OperationsList from 'components/OperationsList'
+import StickyBackToTop from 'components/StickyBackToTop'
 
 import AccountHeader from './AccountHeader'
 import EmptyStateAccount from './EmptyStateAccount'
@@ -181,6 +182,7 @@ class AccountPage extends PureComponent<Props, State> {
               />
             </Box>
             <OperationsList account={account} title={t('app:account.lastOperations')} />
+            <StickyBackToTop />
           </Fragment>
         ) : (
           <EmptyStateAccount account={account} />

src/components/DashboardPage/index.js

@@ -25,6 +25,7 @@ import Box from 'components/base/Box'
 import PillsDaysCount from 'components/PillsDaysCount'
 import Text from 'components/base/Text'
 import OperationsList from 'components/OperationsList'
+import StickyBackToTop from 'components/StickyBackToTop'
 
 import AccountCard from './AccountCard'
 import AccountsOrder from './AccountsOrder'
@@ -174,6 +175,7 @@ class DashboardPage extends PureComponent<Props, State> {
                   withAccount
                 />
               )}
+              <StickyBackToTop />
             </Fragment>
           </Fragment>
         ) : (

src/components/StickyBackToTop.js

@@ -0,0 +1,94 @@
+// @flow
+import React, { PureComponent } from 'react'
+import ReactDOM from 'react-dom'
+import PropTypes from 'prop-types'
+import styled from 'styled-components'
+import Box from 'components/base/Box'
+import ArrowUp from 'icons/ArrowUp'
+
+const Container = styled(Box)`
+  position: fixed;
+  z-index: 10;
+  bottom: 100px;
+  right: 20px;
+  border-radius: 50%;
+  box-shadow: 0 2px 4px 0 rgba(102, 102, 102, 0.25);
+  cursor: pointer;
+  height: 36px;
+  width: 36px;
+  color: white;
+  background-color: #6490f1;
+  transition: all 0.5s;
+  opacity: ${p => (p.visible ? 1 : 0)};
+  pointer-events: ${p => (!p.visible ? 'none' : 'initial')};
+
+  &:focus {
+    width: 200px;
+  }
+`
+
+type Props = {
+  scrollThreshold: number,
+}
+
+type State = {
+  visible: boolean,
+}
+
+class StickyBackToTop extends PureComponent<Props, State> {
+  static contextTypes = {
+    // FIXME when we move to "real" scroll container, potential solution (instead of context): http://greweb.me/2016/09/relay-scrolling-connections/
+    getScrollbar: PropTypes.func,
+  }
+
+  static defaultProps = {
+    scrollThreshold: 800,
+  }
+
+  state = {
+    visible: false,
+  }
+
+  componentDidMount() {
+    this.context.getScrollbar(scrollbar => {
+      const listener = () => {
+        const { scrollTop } = scrollbar
+        const visible = scrollTop > this.props.scrollThreshold
+        this.setState(previous => {
+          if (previous.visible !== visible) {
+            return { visible }
+          }
+          return null
+        })
+      }
+      scrollbar.addListener(listener)
+      this.releaseListener = () => scrollbar.removeListener(listener)
+    })
+  }
+
+  componentWillUnmount() {
+    this.releaseListener()
+  }
+
+  onClick = () => {
+    this.context.getScrollbar(scrollbar => {
+      scrollbar.scrollTo(0, 0, 400)
+    })
+  }
+
+  releaseListener = () => {}
+
+  render() {
+    const { visible } = this.state
+    const el = document.getElementById('sticky-back-to-top-root')
+    if (!el) return null
+    return ReactDOM.createPortal(
+      <Container align="center" justify="center" visible={visible} onClick={this.onClick}>
+        <ArrowUp size={16} />
+      </Container>,
+      el,
+    )
+  }
+}
+
+export default StickyBackToTop

src/components/base/Box/index.js

@@ -72,6 +72,7 @@ const Box = styled.div`
     margin-left: ${p => (p.horizontal && p.flow ? `${p.theme.space[p.flow]}px` : '')};
   }
 `
+// ^FIXME this `> * + * happen for all Box but we only need it when we do "grids".. which is not often. margin should be made explicit on user land.
 
 const RawCard = styled(Box).attrs({ bg: 'white', p: 3, boxShadow: 0, borderRadius: 1 })``
 

src/components/layout/Default.js

@@ -63,6 +63,8 @@ class Default extends Component<Props> {
             <ModalComponent key={name} />
           ))}
 
+          <div id="sticky-back-to-top-root" />
+
           <Box grow horizontal bg="white">
             <SideBar />