Well, this should be so simple. If you keep JSON data in a Javascript variable, then the way you tried should work. See my version of it.

var jsonData = {
    "page" : 1,
    "results" : [{
            "adult" : false,
            "backdrop_path" : "/fLL6WfUXvdQee1fD4xuzNnWfVBk.jpg",
            "genre_ids" : [27, 9648, 80],
            "id" : 176,
            "original_language" : "en",
            "original_title" : "Saw",
            "overview" : "Obsessed with teaching his victims the value of life, a deranged, sadistic serial killer abducts the morally wayward. Once captured, they must face impossible choices in a horrific game of survival. The victims must fight to win their lives back, or die trying...",
            "release_date" : "2004-01-19",
            "poster_path" : "/dHYvIgsax8ZFgkz1OslE4V6Pnf5.jpg",
            "popularity" : 2.897462,
            "title" : "Saw",
            "video" : false,
            "vote_average" : 7.1,
            "vote_count" : 657
        }, {
            "adult" : false,
            "backdrop_path" : "/yKATxJtGY67cXdOmlbWwW6EgPqn.jpg",
            "genre_ids" : [27, 53, 80],
            "id" : 663,
            "original_language" : "en",
            "original_title" : "Saw IV",
            "overview" : "Jigsaw and his apprentice Amanda are dead. Now, upon the news of Detective Kerry's murder, two seasoned FBI profilers, Agent Strahm and Agent Perez, arrive in the terrified community to assist the veteran Detective Hoffman in sifting through Jigsaw's latest grisly remains and piecing together the puzzle. However, when SWAT Commander Rigg is abducted and thrust into a game, the last officer untouched by Jigsaw has but ninety minutes to overcome a series of demented traps and save an old friend...or face the deadly consequences.",
            "release_date" : "2007-10-25",
            "poster_path" : "/veApHw5ARGHWf3ptKf30rOGFY9n.jpg",
            "popularity" : 2.449196,
            "title" : "Saw IV",
            "video" : false,
            "vote_average" : 5.8,
            "vote_count" : 257
        }
    ]
};

console.log(jsonData.results[0].id);
console.log(jsonData.results[1].id);

//By using jquery json parser    
var obj = $.parseJSON('{"name": "", "skills": "", "jobtitel": "Entwickler", "res_linkedin": "GwebSearch"}');
alert(obj['jobtitel']);

//By using javasript json parser
var t = JSON.parse('{"name": "", "skills": "", "jobtitel": "Entwickler", "res_linkedin": "GwebSearch"}');
alert(t['jobtitel'])

Check this jsfiddle

As of jQuery 3.0, $.parseJSON is deprecated. To parse JSON strings use the native JSON.parse method instead.

Source: http://api.jquery.com/jquery.parsejson/

You have it the wrong way round - JSON.stringify turns a javascript object to a string. And JSON.parse parses a JSON String to a javascript object.

Also, having done that, if you want to read a property using a string use square bracket notation:

var jsonData = JSON.parse(data);
var jsonVar = "jVar";

for (var l = 0; l < jsonData[jsonVar].length; l++) {
  var arrayItem = jsonData[jsonVar][l];
 ...
}

(As an aside l is a bad choice for a loop control variable - looks too much like a 1)

JSON content is basically represented as an associative array in JavaScript. You just need to loop over them to either read the key or the value:

    var JSON_Obj = { "one":1, "two":2, "three":3, "four":4, "five":5 };

    // Read key
    for (var key in JSON_Obj) {
       console.log(key);
       console.log(JSON_Obj[key]);
   }

There are two ways to access properties of objects:

var obj = {a: 'foo', b: 'bar'};

obj.a //foo
obj['b'] //bar

Or, if you need to dynamically do it:

var key = 'b';
obj[key] //bar

If you don't already have it as an object, you'll need to convert it.

For a more complex example, let's assume you have an array of objects that represent users:

var users = [{name: 'Corbin', age: 20, favoriteFoods: ['ice cream', 'pizza']},
             {name: 'John', age: 25, favoriteFoods: ['ice cream', 'skittle']}];

To access the age property of the second user, you would use users[1].age. To access the second "favoriteFood" of the first user, you'd use users[0].favoriteFoods[2].

Another example: obj[2].key[3]["some key"]

That would access the 3rd element of an array named 2. Then, it would access 'key' in that array, go to the third element of that, and then access the property name some key.

As Amadan noted, it might be worth also discussing how to loop over different structures.

To loop over an array, you can use a simple for loop:

var arr = ['a', 'b', 'c'],
    i;
for (i = 0; i < arr.length; ++i) {
    console.log(arr[i]);
}

To loop over an object is a bit more complicated. In the case that you're absolutely positive that the object is a plain object, you can use a plain for (x in obj) { } loop, but it's a lot safer to add in a hasOwnProperty check. This is necessary in situations where you cannot verify that the object does not have inherited properties. (It also future proofs the code a bit.)

var user = {name: 'Corbin', age: 20, location: 'USA'},
    key;

for (key in user) {
    if (user.hasOwnProperty(key)) {
        console.log(key + " = " + user[key]);
    }
}    

(Note that I've assumed whatever JS implementation you're using has console.log. If not, you could use alert or some kind of DOM manipulation instead.)