var cars = [{id:"0", name:"bmw"}, {id:0, name:"honda"}, {id:0, name:"lexus"}];

​

​

function assignIds(cars) {

    var i;

    var prefix = 100;

    for(i = 0; i<cars.length; i ++) {

        cars[i]["id"] = function(j) {

            return prefix +j;

        }(i);

    }

    return cars;

}

​

(function doit() {

    console.log("assigning ids to the cars");

    assignIds(cars);

    console.log(assignIds(cars));

}());