Printing nested JSON without using variable names

Question

a web service returns the following nested json object:

{"age":"21-24","gender":"Male","location":"San Francisco, CA","influencer score":"70-79","interests":{"Entertainment":{"Celebrities":{"Megan Fox":{},"Michael Jackson":{}},},"Social Networks & Online Communities":{"Web Personalization": {},"Journals & Personal Sites": {},},"Sports":{"Basketball":{}},},"education":"Completed Graduate School","occupation":"Professional/Technical","children":"No","household_income":"75k-100k","marital_status":"Single","home_owner_status":"Rent"}

i just want to iterate through this object without specifying property name, i tried the following code :

for (var data in json_data) {
 alert("Key:" + data + " Values:" + json_data[data]);
}

however it prints value as [object Object] if it's a nested value, is there any way to keep iterating deeper into nested values ?

Answer 1

Try this:

function iter(obj) {
 for (var key in obj) {
 if (typeof(obj[key]) == 'object') {
 iter(obj[key]);
 } else {
 alert("Key: " + key + " Values: " + obj[key]);
 }
 }
}

BB: added + to prevent error.

• John Hartsock: typeof(someObject) returns "object" not "Object"...Note the lowercase "o"

Answer 2

You can do this recursively.

function alertobjectKeys(data) {
 for (var key in data) {
 if (typeof(data[key]) == "object" && data[key] != null) {
 alertobjectKeys(data[key]);
 } else {
 alert("Key:" + key + " Values:" + data[key]);
 }
 }
}

• g.d.d.c: Inside your nested call you need data[key] - otherwise you're simply reiterating the same object you received.

Answer 3

This of course requires recursion

(function(obj) {
 for (var key in obj) if (obj.hasOwnProperty(key)) {
 if (typeof obj[key] == 'object' && obj[key] !== null)
 arguments.callee(obj[key]);
 else 
 alert("Key: " + key + " Values: " + obj[key]);
 }
)(json_data));

• palswim: Doesn't require recursion, but recursion can help if your data isn't ridiculously large.

Answer 4

function recursiveParse(variable) { 
 for (var key in variable) {
 if ((is_object(variable[key])) || (is_array(variable[key]))) {
 recursiveParse(variable[key]);
 } else {
 // Process variable here
 }
 }
}

Then just call that function with the parameter being the json data, it will parse through the remaining objects and arrays recursively.

• Amr Ellafy: where are the definition for is_object() and is_array() ?
• Anthony Corbelli: In another library I forgot to tell you about but am so used to that I forgot it wasn't core javascript. I apologize.

Answer 5

You can always create a recursive function:

function alertObj(obj) {
 for (var data in obj) {
 if(typeof(obj[data]) === "object")
 alertObj(obj[data]);
 else
 alert("Key:" + data + " Values:" + obj[data]);
 }
}

As long as you aren't worried about recursing too far (which you probably don't need to with JSON objects).

You can also do this with a queue or stack (array) structure:

function alertObj_queue(obj) { // Breadth-first
 var arrPrint = [{key:"Object", data:obj}]; // Initialize array with original object
 for(var i = 0; i < arrPrint.length; i++) {
 if(typeof(arrPrint[i].data) === "object") {
 for(var k in arrPrint[i].data) { // Add each to end of array
 arrPrint.push({key: k, data: arrPrint[i].data[k]});
 }
 alert("Object key: " + arrPrint[i].key);
 } else {
 alert("Key:" + arrPrint[i].key + " Values:" + arrPrint[i].data);
 }
 }
}
function alertObj_stack(obj) { // Depth-first
 var arrPrint = [{key:"Object", data:obj}]; // Initialize array with original object
 while(arrPrint.length) {
 var o = arrPrint.pop();
 if(typeof(o.data) === "object") {
 for(var k in o.data) { // Add each to end of array
 arrPrint.push({key: k, data: o.data[k]});
 }
 alert("Object key: " + o.key);
 } else {
 alert("Key:" + o.key + " Values:" + o.data);
 } 
 }
}

• John Hartsock: your code is not right. You pass in obj but use json_data in your for loop....json_data is undefined.
• Amr Ellafy: unfortunately both does not work, they only go through the 1st level
• palswim: @HeoQue: You only see alerts on the first level because in your data, everything below the first level is an object, so the loop will look at "Sports" and see that it's an object, then go down to "Basketball" and see that it's also an object, so it won't alert for any of those. It would probably make things easier to have some of your JSON data as arrays ("Sports", "Celebrities", etc.).

Answer 6

I'm guessing that in your request (assuming it's Ajax) you aren't specifying the dataType to be returned as 'json'.