Fil is a json file decorator
npm install fil-file --save
var filFile = require('fil-file');
var fileDef =
[{
key: "$startDate",
value: "2017-01-23T00:00:00.001Z"
},
{
key: "$endDate",
value: "2017-01-30T00:00:00.001Z"
}];
filFile.parse(testData, fileDef, function (result) {
console.log(result);
});