我认为值得指出的是，jQuery使用$.each（）很好地解决了这个问题。

请参见：.each（）

例子：

$('.foo').each(function() {
    console.log($(this));
});

$（this）是对象内的单个项目。如果不想使用jQuery的选择器引擎，请将$（'.foo'）转换为变量。

for(var k in validation_messages) {
    var o = validation_messages[k];
    do_something_with(o.your_name);
    do_something_else_with(o.your_msg);
}

var validation_messages = {
    "key_1": {
        "your_name": "jimmy",
        "your_msg": "hello world"
    },
    "key_2": {
        "your_name": "billy",
        "your_msg": "foo equals bar"
    }
}
for (var i in validation_messages) {
    console.log("i = \"" + i + "\"");
    console.log("validation_messages[\"" + i + "\"] = ");
    console.log(validation_messages[i]);
    console.log("\n");
    for (var j in validation_messages[i]) {
        console.log("j = \"" + j + "\"");
        console.log("validation_messages[\"" + i + "\"][\"" + j + "\"] = \"" + validation_messages[i][j] + "\"");
        console.log("\n");
    }
    console.log('\n');
}

输出：

i = "key_1"
validation_messages["key_1"] = 
{
  your_name:"jimmy",
  your_msg:"hello world"
}

j = "your_name"
validation_messages["key_1"]["your_name"] = "jimmy"

j = "your_msg"
validation_messages["key_1"]["your_msg"] = "hello world"


i = "key_2"
validation_messages["key_2"] = 
{
  your_name:"billy",
  your_msg:"foo equals bar"
}

j = "your_name"
validation_messages["key_2"]["your_name"] = "billy"

j = "your_msg"
validation_messages["key_2"]["your_msg"] = "foo equals bar"

使用Undercore.js的_.each：

_.each(validation_messages, function(value, key){
    _.each(value, function(value, key){
        console.log(value);
    });
});

我认为值得指出的是，jQuery使用$.each（）很好地解决了这个问题。

请参见：.each（）

例子：

$('.foo').each(function() {
    console.log($(this));
});

$（this）是对象内的单个项目。如果不想使用jQuery的选择器引擎，请将$（'.foo'）转换为变量。

AgileJon答案的优化和改进版本：

var key, obj, prop, owns = Object.prototype.hasOwnProperty;

for (key in validation_messages ) {

    if (owns.call(validation_messages, key)) {

        obj = validation_messages[key];

        for (prop in obj ) {

            // Using obj.hasOwnProperty might cause you headache if there is
            // obj.hasOwnProperty = function(){return false;}
            // but 'owns' will always work
            if (owns.call(obj, prop)) {
                console.log(prop, "=", obj[prop]);
            }
        }
    }
}