使用Node.js讀取Json文件

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"
  }  
]

我如何僅使用符號訪問沒有數組索引的內部每個對象。 今天，我有一個遍歷所有數組的for循環：

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] );

}

如果我將Json文件更改為以下格式：

{ "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

您可以使用簡單的for循環進行迭代

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)將返回["APPL", "NVDA", "GOOG"]

---

檢查GOOG是否存在，您可以執行此操作

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

演示

Answer 2

如果我理解正確，那么您將使用第二種格式嗎？

這使得它很簡單：

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

console.log(goog);

否則，如果您想查詢原始數組，可以：

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這確實是一個壞習慣。 ;）