batchdelete.js

function deleteListItems() {
    
    var clientContext = SP.ClientContext.get_current();
    var oList = clientContext.get_web().get_lists().getByTitle('TestList');
        
    
    for(var i = 0; i<= 5; i++){
    
        var oListItem = oList.getItemById(i);  
        oListItem.deleteObject();
    }
    
    clientContext.executeQueryAsync(onQuerySucceeded, onQueryFailed);
}

function onQuerySucceeded() {

    alert('Items Deleted');
}

function onQueryFailed(sender, args) {

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