从jQuery GET传递或返回JSON对象 [英] Pass or return JSON Object from jQuery GET

问题描述

我有一个函数，该函数对嵌套的JSON对象发出GET请求.该对象已成功返回，但是您无法访问该返回对象内的其他对象.

I have a function that makes a GET request for a nested JSON object. The object is returned successfully but you can't access the other objects within the returned object.

对象看起来像这样:

{
    "student": {
        "hobbies": ["reading", "dancing", "music"], 
        "subjects": ["english", "maths", "science"]
    }
}

这是函数:

var superObject = {

    getData: function(obj) {
        $.get(obj.target, function(callbackObject) {
            // It works fine if i log callbackObject
            // console.log(callbackObject);
            return callbackObject;
        }
    },

    useData: function() {
        var data = superObject.getData({'target': 'file.json'});
        var hobbies = data.student.hobbies;
        console.log(hobbies); // This fails and returns nothing.
    }
}

推荐答案

问题是您要从$ .get 回调中返回callbackObject，而不是从getData函数中返回. $ .get是异步，因此直到getData()完成很长时间之后，它的回调函数才会触发.这就是为什么您看到未定义的原因.

The problem is that you're returning callbackObject from your $.get callback, and not from your getData function. $.get is asynchronous, so its callback will not fire until long after getData() has finished. That's why you're seeing undefined.

那又怎么样呢?

var superObject = {
    getReuslts: {},

    getData: function(obj) {
        $.get(obj.target, function(callbackObject) {
            getReuslts = callbackObject;
            this.useData();
        }
    },

    useData: function() {
        var hobbies = getReuslts.student.hobbies;
        console.log(hobbies); 
    }
}

当然，这会在useData和getData之间创建一个时间依赖性.为什么不在函数中创建此对象，以便添加一些封装?

Of course this would create a temporal dependency between useData and getData. Why not create this object in a function so you can add some encapsulation?

funcition getSuperObject = {
    var result = {};
    var getReuslts = {};

    function useData() {
        var hobbies = getReuslts.student.hobbies;
        console.log(hobbies); 
    }

    result.getData = function(obj) {
        $.get(obj.target, function(callbackObject) {
            getReuslts = callbackObject;
            useData();
        });
    };
    return result;
}

或提供您自己的回调:

var superObject = {    
    getData: function(obj, callback) {
        $.get(obj.target, function(callbackObject) {
            if (callback)
                callback(calbackObject);
        });
    }
}

然后

superObject.getData({'target': 'file.json'}, function(result) {
    var hobbies = result.student.hobbies;
    console.log(hobbies); // This fails and returns nothing.
});

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