Get Sub Webs

var context = SP.ClientContext.get_current();
var webs = context.get_web().get_webs();
context.load(webs);
context.executeQueryAsync(function (sender, args) {
    var webEnum = webs.getEnumerator();
    while (webEnum.moveNext()) {
        var web = webEnum.get_current();
        alert(web.get_title());
    }
}, function () {
    alert('err');
});