How to loop over object with unknown keys and values

Question

I get a JSON response of shoe sizes from an API endpoint that looks like this:

data: [{
    0: {
        system: "US",
        sizes: {
            7: {B: 3, C: 6, D: 1, E: 1}
            7.5: {A: 6, B: 7, C: 14, D: 11, E: 2}
            8: {2E: 1, A: 5, B: 32, C: 38, D: 23, …}
            8.5: {2E: 2, A: 9, B: 56, C: 79, D: 61, …}
            9: {2A: 5, 2E: 4, A: 17, B: 92, C: 143, …}
            9.5: {2A: 3, 2E: 3, A: 26, B: 132, C: 194, …}
            10: {2A: 5, 2E: 3, 3A: 1, A: 53, B: 159, …}
        }
    }
}]

The data shows e.g that US size 7 has four different kinds of shapes (B, C, D, E) where 3 people have foots of shape B. In total, 11 people has size 7. The list can contain sizes in US, EU or different systems, and key of shapes can be A-Z or basically anything else.

I want to loop over sizes and create a diagram of how many people that has a certain size, and how many has a certain shape of that size.

What would be the best way to loop over an object like this to get the value of every shape? I would expect it to be an array of sizes.

ES6 or ES7 is fine but I would prefer to do it without jQuery.

EDIT: Let me be more clear. First of all I have considered improving data structure but unfortunately that's not an option.

I have tried Object.keys(sizes) which returns an array of the keys. Sure that's one step forward. But I would like to call a function that returns an object with the keys and its values. In my mind, that return value should be something like this:

sizes: [
    {
        size: 7,
        total: 11
        shapes: [
            {name: 'B', value: 3},
            {name: 'C', value: 6},
            {name: 'D', value: 1},
            {name: 'E', value: 1}
        ]
    },{...},{...}
]

Does that makes sense? Of course, length is not absolutely necessary to include in the object.

Answer 1

You can extract all of the keys of an object into an array and simply iterate over that array.

var obj = {
  'key1': 'val1',
  'key2': 'val2'
}
var keys = Object.keys(obj); // ['key1', 'key2']
keys.forEach( function(key) {
  var values = obj[key]
  console.log(values)
  // do stuff with "values"
})

---

Reference -

• Object.keys()