Javascript find json value

I need to search inside a json list of countries. The json is like:

[ {"name": "Afghanistan", "code": "AF"}, {"name": "Åland Islands", "code": "AX"}, {"name": "Albania", "code": "AL"}, {"name": "Algeria", "code": "DZ"}]

I get from database only the code and would output the entire name. So if I get "AL" I would like to retrieve from json "Albania"

I suggest using JavaScript's Array method filter() to identify an element by value. It filters data by using a "function to test each element of the array. Return true to keep the element, false otherwise.."

The following function filters the data, returning data for which the callback returns true, i.e. where data.code equals the requested country code.

function getCountryByCode(code) {
  return data.filter(
      function(data){ return data.code == code }
  );
}

var found = getCountryByCode('DZ');

See the demonstration below:

var data = [{
  "name": "Afghanistan",
  "code": "AF"
}, {
  "name": "Åland Islands",
  "code": "AX"
}, {
  "name": "Albania",
  "code": "AL"
}, {
  "name": "Algeria",
  "code": "DZ"
}];


function getCountryByCode(code) {
  return data.filter(
    function(data) {
      return data.code == code
    }
  );
}

var found = getCountryByCode('DZ');

document.getElementById('output').innerHTML = found[0].name;

<div id="output"></div>

Here's a JSFiddle.

var obj = [
  {"name": "Afghanistan", "code": "AF"}, 
  {"name": "Åland Islands", "code": "AX"}, 
  {"name": "Albania", "code": "AL"}, 
  {"name": "Algeria", "code": "DZ"}
];

// the code you're looking for
var needle = 'AL';

// iterate over each element in the array
for (var i = 0; i < obj.length; i++){
  // look for the entry with a matching `code` value
  if (obj[i].code == needle){
     // we found it
    // obj[i].name is the matched result
  }
}

Just use the ES6 find() function in a functional way:

var data=[{name:"Afghanistan",code:"AF"},{name:"Åland Islands",code:"AX"},{name:"Albania",code:"AL"},{name:"Algeria",code:"DZ"}];

let country = data.find(el => el.code === "AL");
// => {name: "Albania", code: "AL"}
console.log(country["name"]);

or Lodash _.find:

var data=[{name:"Afghanistan",code:"AF"},{name:"Åland Islands",code:"AX"},{name:"Albania",code:"AL"},{name:"Algeria",code:"DZ"}];

let country = _.find(data, ["code", "AL"]);
// => {name: "Albania", code: "AL"}
console.log(country["name"]);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

First convert this structure to a "dictionary" object:

dict = {}
json.forEach(function(x) {
    dict[x.code] = x.name
})

and then simply

countryName = dict[countryCode]

For a list of countries this doesn't matter much, but for larger lists this method guarantees the instant lookup, while the naive searching will depend on the list size.

Making more general the @showdev answer.

var getObjectByValue = function (array, key, value) {
    return array.filter(function (object) {
        return object[key] === value;
    });
};

Example:

getObjectByValue(data, "code", "DZ" );