Cleaner way to get a key and value from JSON - json

Question

Currently the way that I am taking a JSON string where I "Don't know the contents" and pulling the keys and the values is as follows:
var arr = [{"manager_first_name":"jim","manager_last_name":"gaffigan"}];
var arrLen = arr.length;
for(var i = 0; i < arrLen; i++){
var myKeys = Object.keys(arr[i]);
var keysLen = myKeys.length;
for(var x = 0; x < keysLen; x++){
keyName = myKeys[x];
keyValueStr = "arr[i]."+keyName;
keyValue = eval(keyValueStr);
console.log(keyName+':'+keyValue);
}
}
There has to be a cleaner and more efficient way of doing this. Any suggestion would be appreciated.

Answer 1

Using jQuery you can use http://api.jquery.com/jQuery.parseJSON/ & Object.keys - Than:
var obj = jQuery.parseJSON('{"manager_first_name":"jim","manager_last_name":"gaffigan"}');
var keys = Object.keys(obj);
jQuery.each(keys,function(k, v){
console.log(v);
console.log(obj[v]);
});

Answer 2

Create an object and initialize it with your JSON:
var arr = [{"manager_first_name":"jim","manager_last_name":"gaffigan"}];
var JSONObject = new MyJSONObject(arr);
in your constructor, set the object's properties.

Answer 3

You could use for-in loop which iterates over the enumerable properties of an object, in arbitrary order.
var arr = [{"manager_first_name":"jim","manager_last_name":"gaffigan"}];
for (var i = 0; i < arr.length; i++) {
var currentObj = arr[i];
for (var item in currentObj) {
console.log(item + " : " + currentObj[item]);
}
}
If your array always have only one item, you could omit the outermost for loop and just use arr[0]
var currentObj = arr[0];
for (var item in currentObj) {
console.log(item + " : " + currentObj[item]);
}