Get all items from list

How do i get all items from list? Here is my code,

function checkFreebookingdateTime() {

getListCalender = document.getElementById('CalenderListDrop').value;
spHostUrl = decodeURIComponent(getQueryStringParameter('SPHostUrl'));
context = new SP.ClientContext.get_current();
parentContext = new SP.AppContextSite(context, spHostUrl);
web = parentContext.get_web();
list = web.get_lists().getByTitle(getListCalender);
context.load(list);

var camlQuery = new SP.CamlQuery();
camlQuery.set_viewXml('<View><RowLimit>1000</RowLimit></View>');
collListItem = list.getItems(camlQuery);

context.load(collListItem);

context.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this.onQueryFailed));

}

function onQuerySucceeded() {

var listItemEnumerator = collListItem.getEnumerator();
while (listItemEnumerator.moveNext()) {
    var oListItem = listItemEnumerator.get_current();
    var listDetails = oListItem.get_item('EventDate') + "  " + oListItem.get_item('EndDate');

    alert(listDetails.toString());

}

}

function onQueryFailed(sender, args) {

alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());

}

i get this error,

TypeError, Unable to set property collListItem or undefined or null reference