Is it possible to return JSON key names based on value without knowing the key's name

Question

Say I have the following JSON file:

{"attributes":
   {
   "blue":true,
   "red":false,
   "green":true,
   "webAtt":
      {
      "webColor": "#EF5689",
      "webSafe":true
      }
   }
}

but lets also say I do not know any JSON nodes except "attributes". How would I go about finding which attributes are true? Is this even possible? If not, must it be hardcoded for each child node of "attributes"?

I would like this done in JavaScript if possible.

EDIT: There is a reason why webAtt is there and its because I want to get "websafe" and not "webAtt" when sweeping.

Your JSON is invalid; the `{` in 'green' will throw a syntax error. I'm assuming you just mean to have the object for green? — Obsidian Age, Mar 20 '17 at 01:46
yes... my bad... this is just an example JSON I made on the fly, not what I am going to be needing the JavaScript for in reality... — Midimistro, Mar 20 '17 at 01:49

Samuel · Answer 1 · 2017-03-20T01:54:44.827

1

Object.keys() returns the enumerable properties of the given object. https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

So you can do Object.keys(obj.attributes) on the object above and it would return ["blue", "red", "green"]. You can then apply a filter to return only the attributes where the value in the object is true.

var obj = {
    "attributes": {
        "blue":true,
        "red":false,
        "green":true
    }
}
console.log(Object.keys(obj.attributes).filter(function(attr) { return obj.attributes[attr] }))

edited Mar 20 '17 at 01:54

answered Mar 20 '17 at 01:41

Samuel

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1

That's nice and all, but I need to return only blue and green since their values are true and red's is not – Midimistro Mar 20 '17 at 01:46
`Object.keys(obj.attributes).filter(function(attr) { return obj.attributes[attr] })` will return the keys where the value of the key is true – Samuel Mar 20 '17 at 01:48
That works 80%, except instead of returning "websafe", it returns "webattrib", which is not what I want. – Midimistro Mar 20 '17 at 02:06
scratch that, it doesn't work at all how I need it to, the modified version below works closer to what I need it to, but its still missing the "websafe" key. – Midimistro Mar 20 '17 at 02:30

score 1 · Accepted Answer · edited May 23 '17 at 12:17

You can do this with a for loop.

var json = {"attributes":
   {
   "blue":true,
   "red":false,
   "green":true,
   "webAtt":
       {
       "webSafe":true,
       "webcolor":"#EF5689"
       }
   }
};

for (var k in json.attributes) {
  if(json.attributes[k]==true){
      console.log(k + ' ' + json.attributes[k]);
  }
  if(whatIsIt(json.attributes[k])=="Object"){
      for(var l in json.attributes[k]){
          if(json.attributes[k][l]==true){
             console.log(l+'  '+json.attributes[k][l]);
          }
      }
  }
}


//See credit below snippet
var stringConstructor = "test".constructor;
var arrayConstructor = [].constructor;
var objectConstructor = {}.constructor;
function whatIsIt(object) {
if (object === null) {
    return "null";
}
else if (object === undefined) {
    return "undefined";
}
else if (object.constructor === stringConstructor) {
    return "String";
}
else if (object.constructor === arrayConstructor) {
    return "Array";
}
else if (object.constructor === objectConstructor) {
    return "Object";
}
else {
    return "don't know";
}
}

Credit for JSON object type Identifier code: How to check if JavaScript object is JSON

Is it possible to return JSON key names based on value without knowing the key's name

2 Answers2