Question

我有以下node.js文件：

[
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
]

如何在没有数组索引的情况下访问每个对象，只使用符号。今天我有一个贯穿所有阵列的for循环：

var fs = require('fs');

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
for (var i=0; i<stocks.length; i++) {
    if (stocks[i].symbol==="GOOG") {
        console.log(i+ " ." , stocks[i] );

}

如果我将Json文件更改为以下格式：

{ "APPL":
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  "NVDA":
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  "GOOG":
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
}

Answer 1

您可以使用简单的for循环来迭代

var obj = { "APPL":
  {
    "name":"Apple inc",
    "symbol":"AAPL",
    "logo":"apple.png",    
    "price":123,
    "prod":"Apple inc, mac, macbook, iphone, ipod, ipad, osx"
  },
  "NVDA":
  {
    "name":"Nvidia Corporation",
    "symbol":"NVDA",  
    "logo":"nvidia.png",
    "price":321,
    "prod":"Nvidia Corporation, gforce, g-force, shield"
  },
  "GOOG":
  {
    "name":"Google inc",
    "symbol":"GOOG", 
    "logo":"google.png",
    "price":321,
    "prod":"search, android, glass, drive, code school"
  }  
};

for(var i=0, keys = Object.keys(obj),len=keys.length; i <len ; i++){
  if(obj[keys[i]].symbol === "GOOG"){
    console.log(i +'.' +obj[keys[i]]);
  }
}

Object.keys(obj)将返回["APPL", "NVDA", "GOOG"]

检查GOOG是否存在，你可以这样做

var result = Object.keys(obj).indexOf('GOOG') > -1;
console.log(result); // will be true

DEMO

Answer 2

如果我理解正确，您将继续使用第二种格式吗？

这使它变得如此简单：

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
var goog = stocks.GOOG;

console.log(goog);

否则，如果您愿意，可以查询原始数组：

var stocks = JSON.parse(fs.readFileSync("stocks.json"));
var goog = stocks.filter(function(stock) { if(stock.symbol == 'AAPL') return true; } );

console.log(goog[0]);

PS。不要使用readFileSync这是非常糟糕的做法。 ;）

使用Node.js读取Json文件

2 个答案: