why SP.ListOperation.Selection.getSelectedList(ctx) is null?

Question

I want to delete multiple selected list items based on the selection in a listview sharepoint webpart, but the problem is when the page is in draft mode it is extracting the list id & selected item id but whenever I publish the page it gives null value in the liest id & of course by this the selected items id becomes blank.

 

Code : 

 

<button onclick="deleteSelectedItem()">Delete</button>

function deleteSelectedItem() {

var context = SP.ClientContext.get_current();

var listID = SP.ListOperation.Selection.getSelectedList(context);

var selectedItems = SP.ListOperation.Selection.getSelectedItems(context);

if (selectedItems.length > 0) {

var lstObject = context.get_web().get_lists().getById(listID);

for (var i = 0; i < selectedItems.length; i++) {

this.lstObjectItem = lstObject.getItemById(selectedItems[i].id);

lstObjectItem.deleteObject();

}

context.executeQueryAsync(Function.createDelegate(this, this.onSuccess), Function.createDelegate(this, this.onFailure));

}

else {

alert("Please Select item !");

}

}

function onSuccess(sender, args) {

alert('Items Deleted');

window.location.href = window.location.href;

}

function onFailure(sender, args) {

alert('Request failed. ' + args.get_message());

Please help me solving this in the published page & explain why it is working in the draft version but not in the published one.