A table that has cells while also allowing arbitrary (albeit user defined) length. Aim is IE11 compatibility.

table_2018June.js

/* Setup */

var _defProp = Object.defineProperty;
var Table = {}; 
function tabulate(o) {
    var entries = []; Object.keys(o).forEach(function(h) {
        if (h !== "length") {entries.push([h, o[h].values, o[h].default])}
    });
    if (o.length === undefined) {
        o.length = Math.max(entries.map(function(e) {return e[1].length}));
    };
    Object.setPrototypeOf(o, Array.prototype);
    entries.forEach(function(pair) {
        var h = pair[0];
        delete o[h];
        _defProp(o, h, {get: function() {return this.map(function(r) {return r[h]})}});
    });
    var row, length = o.length;
    for (var i = 0; i < length; i++) {
        o[i] = row = {};
        entries.forEach(function(pair) {
            var h = pair[0], val = pair[1][i], j = i;
            var c = (val !== undefined) ? val : pair[2];
            _defProp(row, h, {configurable: true, get: function() {
                delete this[h];
                return this[h] = (typeof c === "function") ? c.call(o, j) : c;
            }});
        })
    };
};

/* Example */

var someTable = {
    __proto__: Table,
    // length: 4,
    tableColumn: {
        values: [
            /* hardcode */ 7,
            /* use default */ ,
            /* formula */ function(rowIdx) {return this[rowIdx - 1].tableColumn + 1},
        ],
        default: function(rowIdx) {return rowIdx * 2},
    }
}

tabulate(someTable);
console.log(someTable[0].tableColumn); // 7
console.log(someTable[1].tableColumn); // 2
console.log(someTable[2].tableColumn); // 3
console.log(someTable.tableColumn); // [7, 2, 3], or with length = 4, [7, 2, 3, 6]
console.log("Length:", someTable.length); // 3, or with length = 4, 4