CSOM Access List

JS

var clientContext = new SP.ClientContext("/");
var web = clientContext.get_web();
var list = web.get_lists().getByTitle("List Name");
var camlQuery = new SP.CamlQuery();
camlQuery.set_viewXml('<View><Query><Where><Eq><FieldRef Name=\'FieldName\'/><Value Type=\'Text\'>X</Value></Eq></Where></Query></View>');
var items = list.getItems(camlQuery);
clientContext.load(items);
clientContext.executeQueryAsync(functionSuccess(), functionFailure);