Looping through JSON with node.js

Question

I have a JSON file which I need to iterate over, as shown below...

{
    \"device_id\": \"8020\",
    \"data\": [{
        \"Timestamp\": \"04-29-11 05:22:39         


        

Answer 1

You may also want to use hasOwnProperty in the loop.

for (var prop in obj) {
    if (obj.hasOwnProperty(prop)) {
        switch (prop) {
            // obj[prop] has the value
        }
    }
}

node.js is single-threaded which means your script will block whether you want it or not. Remember that V8 (Google's Javascript engine that node.js uses) compiles Javascript into machine code which means that most basic operations are really fast and looping through an object with 100 keys would probably take a couple of nanoseconds?

However, if you do a lot more inside the loop and you don't want it to block right now, you could do something like this

switch (prop) {
    case 'Timestamp':
        setTimeout(function() { ... }, 5);
        break;
    case 'Start_Value':
        setTimeout(function() { ... }, 10);
        break;
}

If your loop is doing some very CPU intensive work, you will need to spawn a child process to do that work or use web workers.