Csom javascript get Document Libraries with particular Content Type

Question

I need to filter result to particular content types fo document library. I cannot seem to retrieve the content type of library. How is this <g class="gr_ gr_29 gr-alert gr_gramm Punctuation multiReplace" data-gr-id="29" id="29">possible.</g>
When I try with  oList.get_contentTypes() <g class="gr_ gr_28 gr-alert gr_spell ContextualSpelling only-del replaceWithoutSep" data-gr-id="28" id="28">object object</g> is being returned.
function retrieveAllListProperties() {
    var clientContext = new SP.ClientContext();
    var oWebsite = clientContext.get_web();
    this.collList = oWebsite.get_lists();
    clientContext.load(collList);
    clientContext.executeQueryAsync(
        Function.createDelegate(this, this.onQuerySucceeded), 
        Function.createDelegate(this, this.onQueryFailed)
function onQuerySucceeded() {
    var listInfo = '';
    var listEnumerator = collList.getEnumerator();
    while (listEnumerator.moveNext()) {
        var oList = listEnumerator.get_current();
        listInfo += 'Title: ' + oList.get_title()  + oList.get_contentTypes() + '\n';
    alert(listInfo);
}

Answer 1

oList.get_contentTypes() returns a collection and hence it needs to be iterated to get information about each content type.
UPDATE
var clientContext = new SP.ClientContext.get_current(); 
var oWebsite = clientContext.get_web();
var collList = oWebsite.get_lists();
clientContext.load(collList, 'Include(ContentTypes, Title)');
clientContext.executeQueryAsync(onQuerySucceeded, onQueryFailed);
function onQuerySucceeded() {
    var listInfo = '';
    var listEnumerator = collList.getEnumerator();
    while (listEnumerator.moveNext()) {
        var oList = listEnumerator.get_current();
        listInfo += 'Title: ' + oList.get_title()  + '\n';
        var ct_enumerator = oList.get_contentTypes().getEnumerator();
        while (ct_enumerator.moveNext()) {
        var ct = ct_enumerator.get_current();
        var contentTypeName = ct.get_name();
        alert(contentTypeName);
    alert(listInfo);
function onQueryFailed(sender, args)
{     alert('error'); }