function obj_size(obj) {
var key, count = 0;
for (key in obj.worker)
if (obj.worker.hasOwnProperty(key))
count++;
return count;
}
const w = '{"worker" : [' +
'{"name":"Tom", "age":37},' +
'{"name":"Olivia", "age":42},' +
'{"name":"Jerry", "age":51},' +
'{"name":"Alessia", "age":29} ]}';
const JSONobj = JSON.parse(w);
const size = obj_size(JSONobj);
for (i = 0; i < size; i++)
console.log(JSONobj.worker[i].name + " " + JSONobj.worker[i].age);
/*
run:
"Tom 37"
"Olivia 42"
"Jerry 51"
"Alessia 29"
*/