Playing with formula evaluation

column.js

// Eval data is coming from a secure source.

var columns = {};

columns['_A1'] = "this.A2";
columns['_A2'] = "3";
columns['_A3'] = "this.A1 + this.A2";

Object.defineProperty(columns, "A1", {
    get: function() {
        return eval(columns['_A1'])
    }
});

Object.defineProperty(columns, "A2", {
    get: function () {
        return columns['_A2'];
    },
    set: function (val) {
        columns['_A2'] = val;
    }
});

Object.defineProperty(columns, "A3", {
    get: function () {
        return eval(columns['_A3'])
    }
});

console.log(columns);
console.log(columns.A1);
console.log(columns.A3);

columns.A2 = 10;

console.log(columns.A1);
console.log(columns.A3);