Create subtask in task list via client javascript in sharepoint 2013

Note: We coucld create new subtask in task list directly, but sometimes we need new subtask from parent and create it by coding auto. the important point is that we should know the item "ParentID", all the subtasks inherit parent task is from the ParentID, and the ParentID is equal the ID of  the ID of parent task, so, when we create a new item in the task list, just set the ParentID of the new item, finally the item will inherit the parent task auto.

Now, I will create a subtask from the parent task with the ParentID.

Here is the code:

function newSubTask(){
	var clientContext = new SP.ClientContext.get_current();
	var oList = clientContext.get_web().get_lists().getByTitle('Task Management');
	var itemCreationInfo = new SP.ListItemCreationInformation();
	this.oListItem = oList.addItem(itemCreationInfo);
	oListItem.set_item('Title', 'new001');
	oListItem.set_item('ParentID', '1');
	oListItem.update();
	clientContext.load(oListItem);
        clientContext.executeQueryAsync(Function.createDelegate(this, this.onQuerySucceeded), Function.createDelegate(this, this        .onQueryFailed));
}

function onQuerySucceeded() {
    alert('Item created: ' + oListItem.get_id());
}

function onQueryFailed(sender, args) {
   alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());
}