为什么console.log显示不正确的对象值？

我什至在介绍这些数字之前console.log，还不明白为什么其中d1包含显示内容[100,200,300]。常规for loop显示d1正确的内部虽然。有人可以解释一下console.logGoogle Chrome中的这种行为/错误吗？https://jsfiddle.net/ZSvyt/

var container = {};
container["0"] = [10, 20, 30];
var d1 = container;

console.log('before console.log');
console.log(d1); // <--- IT DISPLAYS [100, 200, 300]. WHY?

// before for loop
console.log('before for loop');
for (var i = 0; i < d1["0"].length; i++) {
    console.log(d1["0"][i]);
}

container["0"] = [100, 200, 300];

console.log('after console.log');
console.log(d1);

// after for loop
console.log('after for loop');
for (var i = 0; i < d1["0"].length; i++) {
    console.log(d1["0"][i]);
}

输出：

before console.log
Object {
    0: Array[3]
}
0: Array[3] 
0: 100
1: 200
2: 300 

before for loop
10
20
30

after console.log
Object {
    0: Array[3]
}
0: Array[3] 
0: 100
1: 200
2: 300

after for loop
100
200
300