Javascript – Get value of key from a nested json

javascriptjqueryjsonnested

I have a (nested) data structure containing objects and arrays. How can I extract the information, i.e. access a specific or multiple values with help of a known key?

For example:

var data = {
    code: 42,
    items: [{
        id: 1,
        category: [{
            cId: 1,
            prodname: 'foo',
            quality: [{
                qId: 012,
                testName: 'micro'
            }, {
                qId: 013,
                testName: 'nano'
            }]
        }, {
            id: 2,
            prodname: 'bar'
        }]
    }]
};

How could I access the value of key quality?

Note: This is a sample JSON object the object is dynamically generated; it is of unknown depth.

Best Answer

That way is correct:

data.items[ 0 ].category[ 0 ].quality;
> [ Object, Object ]

Related Solutions

Javascript – Remove properties from objects (JavaScript)

To remove a property from an object (mutating the object), you can do it like this:

delete myObject.regex;
// or,
delete myObject['regex'];
// or,
var prop = "regex";
delete myObject[prop];

Demo

var myObject = {
    "ircEvent": "PRIVMSG",
    "method": "newURI",
    "regex": "^http://.*"
};
delete myObject.regex;

console.log(myObject);

For anyone interested in reading more about it, Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog, Understanding delete. It is highly recommended.

If you'd like a new object with all the keys of the original except some, you could use the destructuring.

Demo

let myObject = {
  "ircEvent": "PRIVMSG",
  "method": "newURI",
  "regex": "^http://.*"
};

const {regex, ...newObj} = myObject;

console.log(newObj);   // has no 'regex' key
console.log(myObject); // remains unchanged

Json – Can comments be used in JSON

No.

The JSON is data only, and if you include a comment, then it will be data too.

You could have a designated data element called "_comment" (or something) that should be ignored by apps that use the JSON data.

You would probably be better having the comment in the processes that generates/receives the JSON, as they are supposed to know what the JSON data will be in advance, or at least the structure of it.

But if you decided to:

{
   "_comment": "comment text goes here...",
   "glossary": {
      "title": "example glossary",
      "GlossDiv": {
         "title": "S",
         "GlossList": {
            "GlossEntry": {
               "ID": "SGML",
               "SortAs": "SGML",
               "GlossTerm": "Standard Generalized Markup Language",
               "Acronym": "SGML",
               "Abbrev": "ISO 8879:1986",
               "GlossDef": {
                  "para": "A meta-markup language, used to create markup languages such as DocBook.",
                  "GlossSeeAlso": ["GML", "XML"]
               },
               "GlossSee": "markup"
            }
         }
      }
   }
}

Best Answer

Related Solutions

Javascript – Remove properties from objects (JavaScript)

Json – Can comments be used in JSON

Related Topic