Iterate through nested json object array

Since myJSONObject.abc contains a list of products it would make more sense to define the property abc as an array. Like this:

var myJSONObject = 
{
"abc":
    [
        [
            {"prod_ver" : "prod 1 ver 1"},
            {"prod_ver" : "prod 1 ver 2"},
        ],
        [
            {"prod_ver" : "prod 2 ver 1"},
            {"prod_ver" : "prod 2 ver 2"},
        ],
        [
            {"prod_ver" : "prod 3 ver 1"},
            {"prod_ver" : "prod 3 ver 2"},
        ]
    ]
};

Then you can iterate over the products and their versions using normal loops:

for(var i = 0; i < myJSONObject.abc.length; i++)
{
    var product = myJSONObject.abc[i];
    for(var j = 0; j < product.length; j++)
    {
        var version = product[j];
    }
}

You could take it slightly further and alter your JSON object's structure a bit to make it more easily understandable.

var catalog = 
{
    "products": [
        {
            "name": "prod 1",
            "versions": [
                "ver 1",
                "ver 2"
            ]
        },
        {
            "name": "prod 2",
            "versions": [
                "ver 1",
                "ver 2"
            ]
        }
    ]
};

for(var i = 0; i < catalog.products.length; i++)
{
    var product = catalog.products[i];
    var productName = product.name;
    for(var j = 0; j < product.versions.length; j++)
    {
        var version = product.versions[j];
    }
}

function z() {
  for (let key in myJSONObject.abc) {
    let value = myJSONObject.abc[key];
    for (let i = 0; i <= value.length; i++) {
      console.log(value[[i]]);
    }
  }
}

myJSONObject.abc is an object with keys like prod_1, prod_2, etc. You can loop through the keys of an object using for-in. So:

var productName;
var productVersionArray;

for (productName in myJSONObject.abc) {
    productVersionArray = myJSONObject.abc[productName];
}

Note that the order of the keys is not defined by the specification and will vary from JavaScript engine to JavaScript engine. If you want to do them in a particular order, you have to get an array of them, sort it in the order you want, and then loop through that array. (In an ES5-enabled environment, you can get an array of the keys of an object from Object.keys(yourObject). But you'd need a shim for older browsers.)

Within that loop, you can loop through the array using a standard for loop:

for (versionIndex = 0; versionIndex < productVersionArray.length; ++versionIndex) {
    // Use `productVersionArray[versionIndex].prod_ver` here
}

Here's an example putting it all together:

(function() {

  var myJSONObject = 
    {
    "abc":
        {
            "prod_1": 
            [
                {"prod_ver" : "prod 1 ver 1"},
                {"prod_ver" : "prod 1 ver 2"}
            ],

            "prod_2": 
            [
                {"prod_ver" : "prod 2 ver 1"},
                {"prod_ver" : "prod 2 ver 2"}
            ],
            "prod_3": 
            [
                {"prod_ver" : "prod 3 ver 1"},
                {"prod_ver" : "prod 3 ver 2"}
            ]
        }
    };

  var productName;
  var productVersionArray;
  var versionIndex;

  for (productName in myJSONObject.abc) {
      productVersionArray = myJSONObject.abc[productName];
      display(productName + " has " + productVersionArray.length + " versions listed");
      for (versionIndex = 0; versionIndex < productVersionArray.length; ++versionIndex) {
        display("* " + productVersionArray[versionIndex].prod_ver);
      }
  }

  function display(msg) {
    var p = document.createElement('p');
    p.innerHTML = String(msg);
    document.body.appendChild(p);
  }

})();

Live Copy | Source

Updated with ES6

  var { products } =
    {
        "products": [
            {
                "name": "prod 1",
                "versions": [
                    "ver 1",
                    "ver 2"
                ]
            },
            {
                "name": "prod 2",
                "versions": [
                    "ver 1",
                    "ver 2"
                ]
            },
            {
                "name": "prod 3",
                "versions": [
                    "ver 1",
                    "ver 2"
                ]
            }
        ]
    };

    let inventory = products.reduce((accumulator, currentValue) => {
        let { name, versions } = currentValue;
        accumulator[name] = versions
        return accumulator
    }, []);

    Object.entries(inventory).forEach((prod) => {
        let prodName = prod[0];
        let prodVers = prod[1].join(", ");
    });