JS read json file and use as an object

问题

I'm trying so get the number of items in the array inside this piece

JSON

{
  "collection" : [
    {
      "item": "apple"
    },
    {
      "item": "banana"
    }]
}

Using the following JS (NodeJS): Updated with answers from user 'elssar'

var data = JSON.parse(fs.readFileSync(filePath));
console.log(data.collection.length);

Expected result: 2

Without specifying the encoding data will be a buffer instead of string (thanks to user nils). JSON.parse should work for both. Now I'm getting an error Unexpected token ? at Object.parse (native). Any idea how to fix this? (using Node 5.2.0)

回答1:

You need to parse the content of the file to JSON.

fs.readFile(filePath, function (error, content) {
    var data = JSON.parse(content);
    console.log(data.collection.length);
});

Or

var data = JSON.parse(fs.readFileSync(filePath));

Alternatively, you could just require json files (the file extension needs to be .json)

var data = require(filePath);
console.log(data.collection.length);

来源：https://stackoverflow.com/questions/34789321/js-read-json-file-and-use-as-an-object