Sharepoint中异步查询中的委托函数

var context = new SP.ClientContext();
var list = context.get_web().get_lists().getByTitle('ListName');
var query = new SP.CamlQuery();
query.set_viewXml('<View><Query><Where><Eq><FieldRef Name="FieldName"/><Value Type="Text">Value</Value></Eq></Where></Query></View>');
var items = list.getItems(query);
context.load(items);
context.executeQueryAsync(onQuerySuccess, onQueryFailed);

function onQuerySuccess() {
    var enumerator = items.getEnumerator();
    while (enumerator.moveNext()) {
        var item = enumerator.get_current();
        console.log(item.get_item('FieldName'));
    }
}

function onQueryFailed(sender, args) {
    console.log('Query failed. Error: ' + args.get_message());
}