var myObj, x;
myObj = {
"last_updated": "2019-11-16 04:28:46",
"catalog_item": {
"display_value": "",
"value": null
},
"hr_criteria": {
"display_value": "US All Employees",
"value": "31df2c2adb61a7003acf30cf9d9619ca"
},
"icon": "success-icon-wand.png",
"active": "1",
"hover_icon": "success-icon-hover-wand.png",
"userFav": [
{
"sys_id": "e83663c3db814410fd0a38ff9d96199e",
"url_target": "_blank",
"icon": "success-icon-wand.png",
"typeString": "Link",
"item_sys_id": "7b2f4535db936b80fd0a38ff9d9619c1",
"hover_icon": "success-icon-hover-wand.png",
"href": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844",
"title": "Wand",
"table": null,
"order": "0"
}
],
"title": "Wand",
"url": {
"display": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844",
"value": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844"
},
"sys_id": "7b2f4535db936b80fd0a38ff9d9619c1",
"url_target": "_blank",
"typeString": "Link",
"checked": true
}

x = myObj["userFav"][0].item_sys_id;

Try below:

var payload =
{
   
   "userFav": [
      {
         "sys_id": "e83663c3db814410fd0a38ff9d96199e",
         "url_target": "_blank",
         "icon": "success-icon-wand.png",
         "typeString": "Link",
         "item_sys_id": "7b2f4535db936b80fd0a38ff9d9619c1",
         "hover_icon": "success-icon-hover-wand.png",
         "href": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844",
         "title": "Wand",
         "table": null,
         "order": "0"
      }
   ],
   "title": "Wand",
   "url": {
      "display": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844",
      "value": "https://myapps.microsoft.com/success.com/signin/WAND/70621e21-d8e5-47d0-ba36-3e9eb4660844"
   },
   "sys_id": "7b2f4535db936b80fd0a38ff9d9619c1",
   "url_target": "_blank",
   "typeString": "Link",
   "checked": true
};


var x= payload.userFav;
var myJSON = JSON.stringify(x);
gs.print(myJSON);
var y='';
for(i in payload.userFav){
y+=payload.userFav[i].item_sys_id;
}
gs.print(y);

I think I understood where I was going wrong. 

Previously I am using Stringify to convert the object to JSON. 

But I got the Item sysid using the below code: 

gs.info('success is:'+input.test.userFav[0].item_sys_id);

output : success is:7b2f4535db936b80fd0a38ff9d9619c1

For every one who helped me , thank  you very much. 

Here , I am trying to pass the value from client controller to Server Script: 

Client Controller : 

$scope.goTo = function(item) {

$scope.data.test = item;

$scope.server.update().then(function(){
console.log($scope.data.test);
});
}

Server Script  :

if(input.test){

gs.info('success is:'+input.test.userFav[0].item_sys_id);
var l0 = new GlideRecord('sp_log');
l0.initialize();
l0.user = gs.getUserName();
l0.type = 'Portal Favorites';
l0.table = 'u_portal_favorites';
l0.id = jinput.test.userFav[0].item_sys_id;
l0.count = '0';
l0.update();
}

Thanks again everyone !

Hi @dheeraaj 

Kindly mark the response as helpful or correct to close the community post.

Thanks,

Vivek Anand