You can use Object.keys(obj) to get named indexes. This will return an array structure which you can use/customize further. A sample use to iterate over object values may look like this

var persons = { 
    john: { age: 23, year:2010},
    jack: { age: 22, year:2011},
    jenny: { age: 21, year:2012}
}

Getting an iterator

var resultArray = Object.keys(persons).map(function(personNamedIndex){
    let person = persons[personNamedIndex];
    // do something with person
    return person;
});

// you have resultArray having iterated objects 

Just use bracket.

let obj = {0: "item A", 1: "item B", 2: "item C"}
console.log([obj]);

There you go.

const xyz = {
'fName': {type: 'string'},
'mName': {type: 'string'},
'lName': {type: 'string'}
};

let arr = [];

for(let k in xyz) {
  arr.push({[k] : xyz[k]});
}

console.log("Object", xyz);
console.log("Array", arr);

You haven't showed enough of your code, so I'm not sure how you instantiate your classes, but in any case you can use the array map function:

class Item {
    name: string;
    desc: string;
    meta: string
}

class ViewItem {
    name: string;
    desc: string;
    hidden: boolean;

    constructor(item: Item) {
        this.name = item.name;
        this.desc = item.desc;
        this.hidden = false;
    }
}

let arr1: Item[];
let arr2 = arr1.map(item => new ViewItem(item));

(code in playground)

Edit

This can be shorter with Object.assign:

constructor(item: Item) {
    Object.assign(this, item);
}

ECMAScript 6 introduces the easily polyfillable Object.assign:

The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.

Object.assign({}, ['a','b','c']); // {0:"a", 1:"b", 2:"c"}

The own length property of the array is not copied because it isn't enumerable.

Also, you can use ES8 spread syntax on objects to achieve the same result:

{ ...['a', 'b', 'c'] }

For custom keys you can use reduce:

['a', 'b', 'c'].reduce((a, v) => ({ ...a, [v]: v}), {}) 
// { a: "a", b: "b", c: "c" }