batchupdate.js

function updateListItems() {
    
    var itemArray = [];
    var clientContext = SP.ClientContext.get_current();
    var oList = clientContext.get_web().get_lists().getByTitle('TestList');
        
    
    for(var i = 1; i<= 5; i++){
    
        var oListItem = oList.getItemById(i);  
        oListItem.set_item('Title', 'My Updated Item!' + i);  
        oListItem.update();
        itemArray[i] = oListItem;
        clientContext.load(itemArray[i]);
    }
    
    clientContext.executeQueryAsync(onQuerySucceeded, onQueryFailed);
}

function onQuerySucceeded() {

    alert('Items Updated');
}

function onQueryFailed(sender, args) {

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