javascript - 在 Firebase JavaScript 中计数

Question

下面有一个示例 JSON 对象:

{
  "product" : [ {
    "description" : "This ball has air it.",
    "id" : "product0",
    "name" : "football",
    "price" : 10
  }, {
    "description" : "Can kick upto long distance.",
    "id" : "product1",
    "name" : "soccer boots",
    "price" : 5
  }, {
    "description" : "Long socks",
    "id" : "product2",
    "name" : "stockings",
    "price" : 2
  }, {
    "description" : "This ball has air it.",
    "id" : "product3",
    "name" : "gloves",
    "price" : 3
  }, {
    "description" : "Wear it pls.",
    "id" : "product4",
    "name" : "jersey",
    "price" : 12
  } ]
}

在 JavaScript 中查找产品数量(计数)的最短方法是什么？ Firebase 是否在 JavaScript 中提供任何查询来查找对象中的计数？

Answer 1

这是一个简单的解决方案。只需从 JSON 对象中获取所需数组的长度即可。

var json = {
  "product": [{
    "description": "This ball has air it.",
    "id": "product0",
    "name": "football",
    "price": 10
  }, {
    "description": "Can kick upto long distance.",
    "id": "product1",
    "name": "soccer boots",
    "price": 5
  }, {
    "description": "Long socks",
    "id": "product2",
    "name": "stockings",
    "price": 2
  }, {
    "description": "This ball has air it.",
    "id": "product3",
    "name": "gloves",
    "price": 3
  }, {
    "description": "Wear it pls.",
    "id": "product4",
    "name": "jersey",
    "price": 12
  }]
};

console.log(json.product.length);

JSON字符串的情况:像这样获取长度

var json = '{  "product" : [ {"description" : "This ball has air it.","id" : "product0","name" : "football","price" : 10  }, {"description" : "Can kick upto long distance.","id" : "product1","name" : "soccer boots","price" : 5  }, {"description" : "Long socks","id" : "product2","name" : "stockings","price" : 2  }, {"description" : "This ball has air it.","id" : "product3","name" : "gloves","price" : 3  }, {"description" : "Wear it pls.","id" : "product4","name" : "jersey","price" : 12  } ]}';

var t = JSON.parse(json);

console.log(t.product.length);