Question

i need to write the final object formed after a lot of async requests to a JSON file.

Here is the layout of my file

var finalObj = {};
for(i=0;i<100;i++){
  request.get("http://example.com/get/" +i,function(err,res,body){
    var tObj = json.parse(body);
    finalObj[tObj.name] = tObj.value;
  })
}

after all the response object is recieved, i want to save the finalObj to a json file. How do i do this?

Answer 1

Note that it should be JSON.parse(body) to parse the body correctly.

The easiest thing to do would be to use a counter which gets incremented upon completion, and detect whether you’re handled all requests;

var finalObj = {};
var counter = 0;

for(i=0;i<100;i++){
  request.get("http://example.com/get/" +i,function(err,res,body){
    var tObj = JSON.parse(body);
    finalObj[tObj.name] = tObj.value;

    if (++counter === i) {
        require('fs').writeFile('foo.txt', JSON.stringify(finalObj), function (err) { 
            if (!err) {
                // celebrate
            }
        }); 
    }
  });
}

See the File System module for details on the file writing side of things; thankfully they’ve got a writeFile function which eases the process of writing to a file.