Wrap in IIFE for improved uglifyjs compression

www/checkout.js

@@ -1,46 +1,50 @@
-const $ = s => document.querySelector(s)
+(function() {
 
-const invoice_id = $('meta[name=invoice-id]').content
-    , poll_url   = $('meta[name=invoice-poll-url]').content
-    , expires_at = $('meta[name=invoice-expiry]').content
-    , iframed    = window.parent !== window
+  const $ = s => document.querySelector(s)
 
-function paid() {
-  if (iframed) {
-    document.body.style.display = 'none'
-    window.parent.postMessage({ type: 'completed', invoice: invoice_id }, '*')
+  const invoice_id = $('meta[name=invoice-id]').content
+      , poll_url   = $('meta[name=invoice-poll-url]').content
+      , expires_at = $('meta[name=invoice-expiry]').content
+      , iframed    = window.parent !== window
+
+  function paid() {
+    if (iframed) {
+      document.body.style.display = 'none'
+      window.parent.postMessage({ type: 'completed', invoice: invoice_id }, '*')
+    }
+    else location.reload()
   }
-  else location.reload()
-}
 
-function expired() {
-  location.reload()
-}
+  function expired() {
+    location.reload()
+  }
 
-(function poll() {
-  const req = new XMLHttpRequest()
-  req.addEventListener('load', ev =>
-    ev.target.status === 204 ? paid()
-  : ev.target.status === 410 ? expired()
-  : ev.target.status === 402 ? poll() // long polling timed-out, re-poll immediately
-  : setTimeout(poll, 10000)) // unknown response, re-poll after delay
+  (function poll() {
+    const req = new XMLHttpRequest()
+    req.addEventListener('load', ev =>
+      ev.target.status === 204 ? paid()
+    : ev.target.status === 410 ? expired()
+    : ev.target.status === 402 ? poll() // long polling timed-out, re-poll immediately
+    : setTimeout(poll, 10000)) // unknown response, re-poll after delay
+
+    req.addEventListener('error', _ => setTimeout(poll, 10000))
+    req.open('GET', poll_url)
+    req.send()
+  })()
+
+  function updateExpiry() {
+    const left = expires_at - (Date.now()/1000|0)
+    if (left > 0) $('.expiry span').innerHTML = formatDur(left)
+    else expired()
+  }
+
+  function formatDur(x) {
+    const m=x/60|0, s=x%60
+    return ''+m+':'+(s<10?'0':'')+s
+  }
+
+  updateExpiry()
+  setInterval(updateExpiry, 1000)
+  $('.expiry').style.display='block'
 
-  req.addEventListener('error', _ => setTimeout(poll, 10000))
-  req.open('GET', poll_url)
-  req.send()
 })()
-
-function updateExpiry() {
-  const left = expires_at - (Date.now()/1000|0)
-  if (left > 0) $('.expiry span').innerHTML = formatDur(left)
-  else location.reload()
-}
-
-function formatDur(x) {
-  const m=x/60|0, s=x%60
-  return ''+m+':'+(s<10?'0':'')+s
-}
-
-updateExpiry()
-setInterval(updateExpiry, 1000)
-$('.expiry').style.display='block'