为什么我在嵌套的循环中得到一个奇怪的结果
Why am I getting a strange result with nested for loops?
我有一些JSON数据，我试图通过使用一些嵌套的for循环来处理这些数据。我得到的结果不是我所期望的。这是我的开始：
data = [
{
"user_id": "54036a265b2fa765099af857",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
}
]
现在，这是我用来处理上述 JSON 的代码：
for (var i = 0; i < data.length; i++) {
for (var j = 0; j < data[i].days.length; j++) {
for (var k = 0; k < data[i].days[j].items.length; k++) {
if (data[i].user_id === data[i].days[j].items[k].user_id) {
data[i].days[j].item_count++;
}
}
}
}
console.log('result = ' + JSON.stringify(data);
我期望的是item_count将包含一个整数，表示当前用户的项目数(由 data[i].user_id 给出(。相反，这是我得到的：
result = [
{
"user_id": "54036a265b2fa765099af857",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 1
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 4
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 1
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 4
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 1
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 4
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
}
]
我做错了什么？
我运行了你的代码，结果是正确的。您可能遇到缓存问题或类似问题：
<html>
<head>
<script>
var data = [
{
"user_id": "54036a265b2fa765099af857",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5589fdbbe1231a40765a71fe",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"days": [
{
"date": "2016-01-14T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-01-15T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "5608a7b0488505351891c91f"
}
],
"item_count": 0
},
{
"date": "2016-01-16T05:00:00.000Z",
"items": [],
"item_count": 0
},
{
"date": "2016-02-08T05:00:00.000Z",
"items": [
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "54036a265b2fa765099af857",
"item_id": "56b26ff70ac237b50d061578"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b119409736e0086c37ed0a"
},
{
"user_id": "5403cffdbd73cc4e0b49bda7",
"item_id": "56b26ff70ac237b50d061578"
}
],
"item_count": 0
},
{
"date": "2016-02-09T05:00:00.000Z",
"items": [],
"item_count": 0
}
]
}
];
for (var i = 0; i < data.length; i++) {
for (var j = 0; j < data[i].days.length; j++) {
for (var k = 0; k < data[i].days[j].items.length; k++) {
if (data[i].user_id === data[i].days[j].items[k].user_id) {
data[i].days[j].item_count++;
}
}
}
}
console.log('result = ' + JSON.stringify(data));
</script>
</head>
<body>
</body>
</html>
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