Fix scope of variable in case of multi instance

Author: Ronan Giron

src/next-handler.js

@@ -1,12 +1,13 @@
 import $ from 'tealight';
 
-let lastResponse = document;
-let nextUrl;
-
 export function nextHandler(pageIndex) {
+  if (!this.lastResponse) {
+    this.lastResponse = document;
+  }
+  let nextUrl;
   let ias = this;
 
-  let nextEl = $(ias.options.next, lastResponse)[0];
+  let nextEl = $(ias.options.next, this.lastResponse)[0];
 
   if (!nextEl) {
     return;
@@ -16,9 +17,9 @@ export function nextHandler(pageIndex) {
 
   return ias.load(nextUrl)
       .then((data) => {
-        lastResponse = data.xhr.response;
+        this.lastResponse = data.xhr.response;
 
-        let nextEl = $(ias.options.next, lastResponse)[0];
+        let nextEl = $(ias.options.next, this.lastResponse)[0];
 
         return ias.append(data.items)
             .then(() => {