Restructuring Table as a class.

alt_table_structure.js

class Table extends Array {
    static get [Symbol.species]() { return Array; } // Fixes map method
    constructor() {
        super();
        Object.defineProperty(this, '_iteratorPairs', {value: []});
        Object.defineProperty(this, '_headings', {value: []});
        for (let {heading:h, iterable:i} of arguments) {
            this._headings.push(h);
            this._iteratorPairs.push([h, i[Symbol.iterator]()]);
            Object.defineProperty(this, h, {get: () => this.map(r => r[h])});
        };
    }
    _eval() {
        Object.defineProperty(this, '_evaled', {value: true});
        if (this._iteratorPairs.length === 0) return this;
        let row, done = false;
        for (;;) {
            this.push(row = {});
            for (let [h, iterator] of this._iteratorPairs) {
                Object.defineProperty(row, h, {
                    configurable: true, // We delete the prop later
                    get() {
                        const item = iterator.next();
                        if (item.done) {done = true; return}
                        delete this[h]; return this[h] = item.value;
                    }
                });
            }
            for (let h of this._headings) { row[h] } // Calculate props in row
            if (done) {this.pop(); return this}
        }
    }
};

let t = new Table(
    {heading: "icons", iterable: ["apple", "banana", "grape"]},
    {heading: "revenue", iterable: [123, 456, 789]},
)

t._eval();

console.log(t);
console.log("t.icons:", t.icons);
t.forEach(v => console.log("Value via forEach:", v))
t.map(v => console.log("Value via map:", v));
console.log("Table iteration:", ...t);