Infinite scroll SharePoint items

infiniteScroll.js

$(function(){
	var setArea = $('#loadarea'),
	loadNum = 1, // 読み込む個数
	loadTxt = 'Now Loading...', // Loading中の表示テキスト
	fadeSpeed = 500; // フェードスピード

	var onclickStr;
	var txt;
	$.ajax({
		url: "/[your site]/_api/web/lists/getbytitle('test')/items?$select=*", 
		method: "GET", 
		headers: { "Accept": "application/json; odata=verbose" },
		success : function(data){
			for (var i=0; i<5; i++) {
				onclickStr = "openInDialog('/[your site]/Lists/test/DispForm.aspx?ID=" + data.d.results[i].ID + "',500,500,true,true,false); return:false;";
				txt = data.d.results[i].Body;
				if(txt.length > 200){txt = txt.substr(0, 200) + "...";}
				$('<div id="' + data.d.results[i].Title + '" class="loadItem"><h3>'
					+ data.d.results[i].Title + '</h3><br>'
					+ txt + ' <a href="javascript:void(0)" onclick=' 
					+ onclickStr + '>' + '[read more]'+ '</a></div>').appendTo(setArea);
			}
		}
	});

	$("#s4-workspace").scroll(function(){
		var winHeight = $("#s4-workspace").height(); 
		var posBottom = $("#s4-bodyContainer").height() - winHeight;
		if($("#s4-workspace").scrollTop() >= posBottom) {
			var adjScrTop = $("#s4-workspace").scrollTop();
			$("#s4-bodyContainer").animate({scrollTop:(adjScrTop)-1},0);
			$.ajax({
				url: "/[your site]/_api/web/lists/getbytitle('test')/items?$select=*", 
				method: "GET", 
				headers: { "Accept": "application/json; odata=verbose" },
				success : function(data){
					var dataLengh = data.d.results.length,
					loadItemLength = setArea.find('.loadItem').length,
					setAdj = (dataLengh)-(loadItemLength),
					setBeg = (dataLengh)-(setAdj);
					if(!(dataLengh == loadItemLength)){
						setArea.append('<div id="nowLoading">' + loadTxt + '</div>');
						if(loadItemLength == 0){
							for (var i=0; i<loadNum; i++) {
								onclickStr = "openInDialog('/[your site]/Lists/test/DispForm.aspx?ID=" + data.d.results[i].ID + ",500,500,true,true,false'); return:false;";
								txt = data.d.results[i].Body;
								if(txt.length > 200){txt = txt.substr(0, 200) + "...";}
								$('<div id="' + data.d.results[i].Title + '" class="loadItem"><h3>'
									+ data.d.results[i].Title + '</h3><br>'
									+ txt + ' <a href="javascript:void(0)" onclick=' 
									+ onclickStr + '>' + '[read more]'+ '</a></div>').appendTo(setArea)
								.css({opacity:'0'}).animate({opacity:'1'},fadeSpeed);
							}
						} else if(loadItemLength > 0 && loadItemLength < dataLengh){
							if(loadNum < setAdj){
								for (var i=0; i<loadNum; i++) {
									v = i+setBeg;
									onclickStr = "openInDialog('/[your site]/Lists/test/DispForm.aspx?ID=" + data.d.results[v].ID + "',500,500,true,true,false); return:false;";
									txt = data.d.results[v].Body;
									if(txt.length > 200){txt = txt.substr(0, 200) + "...";}
									$('<div id="' + data.d.results[v].Title + '" class="loadItem"><h3>'
										+ data.d.results[v].Title + '</h3><br>'
										+ txt + ' <a href="javascript:void(0)" onclick=' 
										+ onclickStr + '>' + '[read more]'+ '</a></div>').appendTo(setArea)
									.css({opacity:'0'}).animate({opacity:'1'},fadeSpeed);
								}
							} else if(loadNum >= setAdj){
								for (var i=0; i<setAdj; i++) {
									v = i+setBeg;
									onclickStr = "openInDialog('/[your site]/Lists/test/DispForm.aspx?ID=" + data.d.results[v].ID + "'500,500,true,true,false); return:false;";
									txt = data.d.results[v].Body;
									if(txt.length > 200){txt = txt.substr(0, 200) + "...";}
									$('<div id="' + data.d.results[v].Title + '" class="loadItem"><h3>'
										+ data.d.results[v].Title + '</h3><br>'
										+ txt + ' <a href="javascript:void(0)" onclick=' 
										+ onclickStr + '>' + '[read more]'+ '</a></div>').appendTo(setArea)
									.css({opacity:'0'}).animate({opacity:'1'},fadeSpeed);
								}
							}
						} else if(loadItemLength == dataLengh){
							return false;
						}
					} else {
						return false;
					}
				},
				complete : function(){
					$('#nowLoading').each(function(){
						$(this).remove();
					});
					return false;
				}
			});
			return false;
		}
	});

    //add button go back to page top
    var topBtn = $('#page-top');
    topBtn.hide();
    $('#s4-workspace').scroll(function () {
        if ($(this).scrollTop() > 400) {
            topBtn.fadeIn();
        } else {
            topBtn.fadeOut();
        }
    });
    topBtn.click(function () {
        $('#s4-workspace').animate({
            scrollTop: 0
        }, 500, "swing");
        return false;
    });
});

//Open item in dialog
function openInDialog(pageUrl, dlgWidth, dlgHeight, dlgAllowMaximize,dlgShowClose,needCallbackFunction){
	var options = {
		url: pageUrl,
		width: dlgWidth,
		height: dlgHeight,
		allowMaximize: dlgAllowMaximize,
		showClose: dlgShowClose
	};
	if(needCallbackFunction){
		options.dialogReturnValueCallback = Function.createDelegate(null, CloseDialogCallback);
	}
	SP.SOD.execute('sp.ui.dialog.js', 'SP.UI.ModalDialog.showModalDialog', options);
}

function CloseDialogCallback(dialogResult, returnValue){
	if(dialogResult == SP.UI.DialogResult.OK){
		//do something
		;
	}else if(dialogResult == SP.UI.DialogResult.cancel){
		;
	}else{
		;
	}
}