javascript - How to iterate down an Array in chunks -

i'm trying build application takes text website (for app i'm using gutenburg.org's open ebook catalog) , displays story in bites of 10 indexes @ time in div make story easier read add. have working increment function i'm stuck how increment previous chunk.

html: <input type="text" id="url" style="width: 400px"> <input type="button" id="btn" value="get json"> <button id="button">next</button> <button id="prev">previous</button> <div id="test"></div> javscript:    $(function() {         $( '#service' ).on( 'change', function(){             $( '#url' ).val( $( ).val() );         });          //angular.module('exampleapp')         $( '#url' ).val( $( '#service' ).val() );          $( '#btn' ).click(function(){             var url = $( '#url' ).val()              $.ajax({               crossorigin: true,               proxy: "http://localhost:8888/whorl/proxy.php",               url: url,               //datatype: "json", //no need. if use crossorigin, datatype override "json"               //charset: 'iso-8859-1', //use define charset of target url               context: {},               success: function(data) {                   //alert(data);                   var body = data;                    console.log(body.length);                   //body/data string                   var text = body.split(' ')                   console.log(text.length);            var increment = function(array) {         if (array.chunk < array.length) {             var chunk =      array.slice(array.chunk,math.min(array.chunk+array.chunksize, array.length).join(" ");             array.chunk += array.chunksize;             $( '#test' ).html(chunk);             console.log(chunk);         }     };              $(document).ready(function(){         $("button").click(function() {           increment(text);          }); });   }         })         .done(function( data, textstatus, jqxhr ) {             //alert(data);         });     }); });  

pass attribute, value either increment or decrement

if (value=='increment')          array.chunk += array.chunksize;  else      array.chunk -= array.chunksize;