Retrieve items from a list (example fail)

Retrieve items from a list

function retrieveListItems(siteUrl) {
    var clientContext = new SP.ClientContext(siteUrl);
    var oList = clientContext.get_web().get_lists().getByTitle('Announcements');

    var camlQuery = new SP.CamlQuery();
    camlQuery.set_viewXml(
        '<View><Query><Where><Geq><FieldRef Name=\'ID\'/>' +
        '<Value Type=\'Number\'>1</Value></Geq></Where></Query>' +
        '<RowLimit>10</RowLimit></View>'
    );
    this.collListItem = oList.getItems(camlQuery);

    clientContext.load(collListItem);
    clientContext.executeQueryAsync(
        Function.createDelegate(this, this.onQuerySucceeded),
        Function.createDelegate(this, this.onQueryFailed)
    );
}

function onQuerySucceeded(sender, args) {
    var listItemInfo = '';
    var listItemEnumerator = collListItem.getEnumerator();

    while (listItemEnumerator.moveNext()) {
        var oListItem = listItemEnumerator.get_current();
        listItemInfo += '\nID: ' + oListItem.get_id() +
            '\nTitle: ' + oListItem.get_item('Title') +
            '\nBody: ' + oListItem.get_item('Body');
    }

    alert(listItemInfo.toString());
}

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

I've modified the code to get items from Documents or from other lists.  When I try it fails.  I'm not sure what is missing. 

My code:

ExecuteOrDelayUntilScriptLoaded(retrieveListItems, "sp.js");
function retrieveListItems(siteUrl) {
    var clientContext = new SP.ClientContext(siteUrl);
    var oList = clientContext.get_web().get_lists().getByTitle('Documents');

    var camlQuery = new SP.CamlQuery();
    //camlQuery.set_viewXml(
    //    '<View><Query><Where><Geq><FieldRef Name=\'ID\'/>' +
    //    '<Value Type=\'Number\'>1</Value></Geq></Where></Query>' +
    //    '<RowLimit>10</RowLimit></View>'
    //);
    this.collListItem = oList.getItems(camlQuery);

    clientContext.load(collListItem);
    clientContext.executeQueryAsync(
        Function.createDelegate(this, this.onQuerySucceeded),
        Function.createDelegate(this, this.onQueryFailed)
    );
}

function onQuerySucceeded(sender, args) {
    console.log('succeed...')
    var listItemInfo = '';
    var listItemEnumerator = collListItem.getEnumerator();

    while (listItemEnumerator.moveNext()) {
        var oListItem = listItemEnumerator.get_current();
        listItemInfo += '\nID: ' + oListItem.get_id() +
            '\nTitle: ' + oListItem.get_item('Title') +
            '\nBody: ' + oListItem.get_item('Body');
    }

    alert(listItemInfo.toString());
}

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

F12 tools show oList is undefined.

var oList = clientContext.get_web().get_lists().getByTitle('Documents');