javascript - 嵌套函数的返回值

Question

这个问题已经有答案了:

How do I return the response from an asynchronous call? (42 个回答)

已关闭 10 年前。

我有一个带有函数的对象。当我以这种方式使用它时，它总是返回 undefined 。我怎样才能让它返回任何this.client[method].read(params).done函数返回？

rest.get('search', {query: 'Eminem', section: 'tracks'})

这是对象:

var rest = {

    // configuration
    base: 'http://localhost/2.0/',
    client: null,

    get: function (method, params) {

        // if client is null, create new rest client and attach to global
        if (!this.client) {
            this.client = new $.RestClient(this.base, {
              cache: 5 //This will cache requests for 5 seconds
            });
        }

        // add new rest method
        if (!this.client[method]) {
            this.client.add(method);
        }

        // make request
        this.client[method].read(params).done(function(response) {
            //'client.foo.read' cached result has expired
            //data is once again retrieved from the server
            return response;
        });
    }
}

Answer 1

get: function (method, params, callback) {

    // if client is null, create new rest client and attach to global
    if (!this.client) {
        this.client = new $.RestClient(this.base, {
          cache: 5 //This will cache requests for 5 seconds
        });
    }

    // add new rest method
    if (!this.client[method]) {
        this.client.add(method);
    }

    // make request
    this.client[method].read(params).done(function(response) {
        //'client.foo.read' cached result has expired
        //data is once again retrieved from the server
        callback(response);
    });
    /*
    simpler solution:
    this.client[method].read(params).done(callback);
    */
}

这是异步代码，因此您必须使用回调:

rest.get('search', {query: 'Eminem', section: 'tracks'}, function(response) {
    // here you handle method's result
})