Formula grid: real formulas, live
Every cell in columns E–J (and every odd column beyond) holds a real formula — =A1+B1, =SUM(A1:D1), =IF(A1>0,B1,C1), a running sum — evaluated by fast-formula-parser (280 Excel functions), with the dependency graph discovered by Vue's tracking rather than parsed up front. The parser loads on demand when you click; nothing runs on page load.
What to notice
- Set A1 to
5000and watch E1, G1, H1, I1 and the J column cascade. - Conditional dependencies are live. Select I1 and flip A1's sign — the tracked dependency set shifts between branches, because the graph is whatever the formula actually read.
- An unrendered cell allocates nothing. The virtualized window mounts a few hundred DOM cells out of up to a million in the model; a formula cell's ref and computed materialize only when observed.
Related guide pages
- Computed & Watch — when
computed()earns its bytes; plainwatchversus$watch. - Computed Seed Pattern — seeding a computed from a plain getter.
- Performance by Design — what the shape costs and does not.
- Interactive Benchmarks — the numbers, run in your browser.
The source
ts
/**
* A single spreadsheet cell, authored per the ivue operating manual.
*
* - raw → ref-getter: the LITERAL text the user typed
* ('42' | 'hello' | '=A1+B2'). Mutable state, `.value` to r/w.
* - value → the ONE computed(): parse + evaluate the formula (or resolve
* the literal). Parsing+evaluating is real work, correctly
* memoized. This is the whole integration seam: the parser's
* onCell/onRange hooks read OTHER cells' `value.value` from
* inside THIS computed's effect, so Vue discovers the formula's
* dependencies automatically — no hand-built dependency graph.
* - display / isFormula / cssClass → PLAIN getters (0 bytes/instance,
* reactive via leaf tracking), exactly the `IvueCell` shape.
*
* Instances are plain objects. None of the getters run at construction, so the
* ref and computed MATERIALIZE LAZILY — a cell that is never rendered never
* allocates a Ref or a Computed. That laziness is the whole point.
*
* The pure logic (parse detection, literal resolution, display, css) is read
* through the sheet's `Logic` seam, so a sheet variant reroutes it for every
* cell at once.
*/
import { computed, ref, type ComputedRef } from 'vue';
import { Reactive } from '../../ivue';
import type { FormulaLogic } from './FormulaLogic';
import type { Sheet } from './Sheet';
class $FormulaCell {
constructor(sheet: Sheet.Model, row: number, col: number, initial: string) {
this.sheet = sheet;
this.row = row;
this.col = col;
this.initialText = initial;
}
// CONSTANTS / CONFIG — plain fields, set once, never mutated.
// `sheet` is an injected dependency (the parser + O(1) cellAt live on it),
// `row`/`col` are the 1-based position used by the parser and ROW()/COLUMN().
readonly sheet: Sheet.Model;
readonly row: number;
readonly col: number;
protected readonly initialText: string;
// MUTABLE STATE — ref-getter; materializes on first touch.
get raw() {
return ref(this.initialText);
}
// HOT DERIVED — the single surgical computed(). Parsing + evaluating is real
// work; memoizing it is exactly the "one hot value" the ivue idiom promotes.
// computed: expensive — parse + evaluate, the one hot value
get value(): ComputedRef<FormulaLogic.CellValue> {
return computed<FormulaLogic.CellValue>(() => this.evaluateText());
}
// DERIVED — plain getters. Reactive via leaf tracking; zero per-instance cost.
get isFormula() {
return this.sheet.Logic.isFormulaText(this.raw.value);
}
get display() {
return this.sheet.Logic.displayOf(this.value.value);
}
get cssClass() {
return this.sheet.Logic.cssOf(this.value.value, this.isFormula);
}
/** The body of the `value` computed — a method, so it is testable and
* overridable without touching the cache. */
evaluateText(): FormulaLogic.CellValue {
const logic = this.sheet.Logic;
const text = this.raw.value;
if (!logic.isFormulaText(text)) return logic.evalLiteral(text);
// The reads inside sheet.evaluate() (onCell/onRange → other cells'
// value.value) are tracked by THIS computed's effect → auto deps.
return this.sheet.evaluate(this, logic.stripFormula(text));
}
// Read every derived value once — used only by the measurement harness to
// force full materialization of all 100k cells for the worst-case number.
touch() {
void this.value.value;
void this.display;
void this.isFormula;
void this.cssClass;
}
}
export namespace FormulaCell {
export const $Class = $FormulaCell; // raw — children `extends` this
export let Class = Reactive($Class); // reactive — you `new` this
export type Model = InstanceType<typeof Class>; // raw-instance type — collections, parameters, returns
export type Instance = typeof Class.Instance;
}ts
/**
* The Sheet — a PLAIN (non-reactive) container that owns the 100,000
* `FormulaCell` instances and the ONE shared formula parser.
*
* The reactivity lives on the cells (each has its own ref + computed); the
* Sheet is just the structure + the integration seam:
*
* - `grid[r0][c0]` holds the cells, giving an O(1) 1-based `cellAt(row,col)`.
* - a SINGLE `FormulaParser` (not one per cell — that would reintroduce the
* per-instance allocation this whole design fights) whose `onCell`/`onRange`
* hooks read cells' `value.value`. Because those reads happen while a cell's
* `value` computed is evaluating, VUE tracks them as real dependencies —
* the dependency graph is discovered, never hand-built.
* - `Logic` — the pure-logic seam. Every cell and every seeding call reads
* the logic class through it, so a sheet subclass reroutes the whole
* layer with one override.
*/
import FormulaParser from 'fast-formula-parser';
import { Static } from '../../Static';
import { FormulaCell } from './FormulaCell';
import { FormulaLogic } from './FormulaLogic';
class $Sheet {
/** The parser's error class, read off the parser module once per class —
* a static so a subclass can substitute the error shape it evaluates to. */
protected static get $FormulaError() {
return (
FormulaParser as unknown as {
FormulaError: new (error: string, details?: unknown) => FormulaLogic.CellValue;
}
).FormulaError;
}
constructor(rows: number, cols: number = FormulaLogic.Class.COLS) {
this.rows = rows;
this.cols = cols;
const { initialFormula } = this.Logic;
const grid: FormulaCell.Model[][] = new Array(rows);
for (let rowIndex = 0; rowIndex < rows; rowIndex++) {
const rowArr: FormulaCell.Model[] = new Array(cols);
for (let columnIndex = 0; columnIndex < cols; columnIndex++) {
rowArr[columnIndex] = new FormulaCell.Class(
this,
rowIndex + 1,
columnIndex + 1,
initialFormula(rowIndex, columnIndex)
);
}
grid[rowIndex] = rowArr;
}
this.grid = grid;
this.parser = new FormulaParser({
onCell: (ref) => this.cellValueAt(ref.row, ref.col),
onRange: (ref) => this.rangeValues(ref as Sheet.RangeRef)
});
}
// CONSTANTS / CONFIG — set once in the constructor, never mutated.
readonly rows: number;
readonly cols: number;
/** [row0][col0] — the cells, doubling as the O(1) cellAt index. */
readonly grid: FormulaCell.Model[][];
/** ONE parser for the entire sheet, shared by all cells. */
protected readonly parser: FormulaParser;
/** Recursion guard: a cell re-entered mid-evaluation is a cycle → #REF!. */
protected readonly evaluating = new Set<object>();
/** When non-null, cellValueAt records every (row,col) read (dep tracing). */
protected tracer: Array<[number, number]> | null = null;
/** The pure-logic layer this sheet (and its cells) reason with — the
* seam a subclass overrides to route the whole layer elsewhere. */
get Logic() {
return FormulaLogic.Class;
}
/** The one cast per class: instance code reads its own statics here. */
protected get self() {
return this.constructor as typeof $Sheet;
}
/** O(1) 1-based lookup. Out of bounds → undefined. */
cellAt(row: number, col: number): FormulaCell.Model | undefined {
if (row < 1 || row > this.rows || col < 1 || col > this.cols) return undefined;
return this.grid[row - 1][col - 1];
}
/**
* onCell seam — read the referenced cell's REACTIVE value. The read is
* tracked by whatever computed is currently evaluating, so editing that cell
* later invalidates the dependent formula automatically.
*/
protected cellValueAt(row: number, col: number): FormulaLogic.CellValue {
if (this.tracer) this.tracer.push([row, col]);
const cell = this.cellAt(row, col);
return cell ? cell.value.value : null; // out of bounds / blank → 0 in math
}
/** onRange seam — a 2D array of the referenced cells' values. */
protected rangeValues(ref: Sheet.RangeRef): FormulaLogic.CellValue[][] {
const { from, to } = ref;
const out: FormulaLogic.CellValue[][] = [];
for (let rowIndex = from.row; rowIndex <= to.row; rowIndex++) {
const rowArr: FormulaLogic.CellValue[] = [];
for (let columnIndex = from.col; columnIndex <= to.col; columnIndex++)
rowArr.push(this.cellValueAt(rowIndex, columnIndex));
out.push(rowArr);
}
return out;
}
/**
* Parse + evaluate a formula body (no leading '='), through the SHARED parser.
* Called from a cell's `value` computed, so every onCell/onRange read inside
* becomes a tracked dependency of that computed. Guarded against cycles.
*/
evaluate(cell: { row: number; col: number }, body: string): FormulaLogic.CellValue {
if (body.trim().length === 0) return null; // "=" alone → blank
const FormulaError = this.self.$FormulaError;
if (this.evaluating.has(cell)) return new FormulaError('#REF!'); // circular ref
this.evaluating.add(cell);
try {
return this.parser.parse(body, {
row: cell.row,
col: cell.col,
sheet: 'Sheet1'
}) as FormulaLogic.CellValue;
} catch (error) {
return error instanceof (FormulaError as unknown as Function)
? (error as FormulaLogic.CellValue)
: new FormulaError('#ERROR!');
} finally {
this.evaluating.delete(cell);
}
}
/**
* Diagnostic: which cells does (row,col)'s formula CURRENTLY read? Re-parses
* once outside Vue tracking with the read-tap on. It walks the exact same
* onCell/onRange path Vue tracks, so the returned set IS the live Vue
* dependency set for that cell — which is why it visibly SHIFTS when an
* IF()'s condition crosses a branch boundary.
*/
traceDeps(row: number, col: number): Array<[number, number]> {
const cell = this.cellAt(row, col);
if (!cell || !cell.isFormula) return [];
const body = this.Logic.stripFormula(cell.raw.value);
if (body.trim().length === 0) return [];
const previous = this.tracer;
this.tracer = [];
try {
this.parser.parse(body, { row, col, sheet: 'Sheet1' });
} catch {
/* keep whatever reads it made before erroring */
}
const recorded = this.tracer;
this.tracer = previous;
const seen = new Set<string>();
const deps: Array<[number, number]> = [];
for (const [rowIndex, columnIndex] of recorded) {
const key = rowIndex + ',' + columnIndex;
if (!seen.has(key)) {
seen.add(key);
deps.push([rowIndex, columnIndex]);
}
}
return deps;
}
/** Iterate every cell — the measurement harness uses this to force full
* materialization of all cells for the worst-case heap figure. */
forEach(visit: (cell: FormulaCell.Model) => void) {
for (let rowIndex = 0; rowIndex < this.rows; rowIndex++) {
const rowArr = this.grid[rowIndex];
for (let columnIndex = 0; columnIndex < this.cols; columnIndex++) visit(rowArr[columnIndex]);
}
}
}
export namespace Sheet {
export const $Class = Static($Sheet); // anchor — it declares a static; children `extends` this
export let Class = $Class; // selection — plain (non-reactive) class, so no Reactive()
/** Raw-instance type — what cells and the page hold. */
export type Model = InstanceType<typeof Class>;
export interface RangeRef {
from: { row: number; col: number };
to: { row: number; col: number };
}
}ts
import { Static } from '../../Static';
/**
* Configuration + PURE cell logic for the formula grid — a static
* capability class, so a variant grid EXTENDS it (`class $WideGridLogic
* extends FormulaLogic.$Class` overriding COLS or initialFormula) instead
* of forking a file of functions.
*
* Nothing here is reactive and nothing here imports the parser — these are
* the plain operations the reactive `FormulaCell` wraps. Keeping them pure
* means the cell class stays a thin reactivity shell (one `computed()` +
* plain getters) and the same operations can be unit-reasoned about in
* isolation. The Sheet exposes this class through its `Logic` seam, which
* is the one place a sheet subclass reroutes the whole layer.
*/
class $FormulaLogic {
/** Grid shape — 40 columns × 2,500 rows = 100,000 cells. */
static readonly COLS = 40;
static readonly ROWS = 2500;
static readonly CELL_COUNT = 40 * 2500; // 100,000
/** The scaled-up option — 40 columns × 25,000 rows = 1,000,000 cells. */
static readonly ROWS_1M = 25000;
/** Row-windowing geometry (identical to the plain grid demo). */
static readonly ROW_HEIGHT = 28; // px
static readonly VIEWPORT_HEIGHT = 448; // px → ~16 rows on screen
static readonly OVERSCAN = 4; // extra rows above/below the viewport
/**
* The running-sum column resets every RUNSUM_BLOCK rows so no dependency
* chain is thousands of levels deep (a cold read of the bottom of a
* full-height chain would recurse through the parser thousands of times).
* A block of 50 keeps the chain shallow while still cascading across ~3
* screens when the top is edited.
*/
static readonly RUNSUM_BLOCK = 50;
/** Spreadsheet-style column label: 0→A, 25→Z, 26→AA … */
static colLabel(columnIndex: number): string {
let label = '';
let remaining = columnIndex + 1;
while (remaining > 0) {
const digit = (remaining - 1) % 26;
label = String.fromCharCode(65 + digit) + label;
remaining = Math.floor((remaining - 1) / 26);
}
return label;
}
/**
* Deterministic numeric input for a data cell: a repeatable mix of
* positives/negatives/decimals with ~8% blanks (so `cssClass` and the
* blank dot vary). Kept purely numeric so the formulas that reference
* these columns never error on the initial data — text can still be typed
* in live. Same (row,col) → same value on every build.
*/
static numData(row: number, col: number): string {
const seed = row * this.COLS + col;
if (seed % 13 === 5) return ''; // ~7.7% blanks
const value = ((seed * 2654435761) % 100000) / 100 - 500; // −500 … 500
return (Math.round(value * 100) / 100).toString();
}
/**
* The literal text every cell starts with — REAL Excel-formula syntax
* wired so roughly half the grid is cross-referencing formulas and the
* other half is the numeric source data they read. `row`/`col` are
* 0-based here; the A1 refs they emit are 1-based.
*
* Column map (per row r = row + 1):
* A B C D (0-3) input numbers — the source data
* E (4) =A+B — cross-cell arithmetic
* F (5) =C-D — cross-cell arithmetic
* G (6) =SUM(A:D) — range, exercises onRange
* H (7) =AVERAGE(A:D) — range, exercises onRange
* I (8) =IF(A>0, B, C) — CONDITIONAL dependency (marquee)
* J (9) =J(r-1)+A (block-reset) — running sum (marquee cascade)
* K…AN(10+) even col = input, odd col = =<left1>+<left2> (cross-column mesh)
*/
static initialFormula(row: number, col: number): string {
const rowNumber = row + 1; // 1-based row for A1 notation
switch (col) {
case 0:
case 1:
case 2:
case 3:
return this.numData(row, col);
case 4:
return `=A${rowNumber}+B${rowNumber}`;
case 5:
return `=C${rowNumber}-D${rowNumber}`;
case 6:
return `=SUM(A${rowNumber}:D${rowNumber})`;
case 7:
return `=AVERAGE(A${rowNumber}:D${rowNumber})`;
case 8:
return `=IF(A${rowNumber}>0,B${rowNumber},C${rowNumber})`;
case 9:
// Running sum, reset at the top of each RUNSUM_BLOCK-row block.
return row % this.RUNSUM_BLOCK === 0
? `=A${rowNumber}`
: `=J${rowNumber - 1}+A${rowNumber}`;
default:
// Filler mesh: even columns are input data; odd columns sum the two
// cells immediately to their left (one data, one formula) — a real
// cross-column dependency, not a decorative one.
if (col % 2 === 0) return this.numData(row, col);
return `=${this.colLabel(col - 1)}${rowNumber}+${this.colLabel(col - 2)}${rowNumber}`;
}
}
/** Does the literal text start (after leading spaces) with '='? */
static isFormulaText(text: string): boolean {
const trimmed = text.trimStart();
return trimmed.length > 0 && trimmed[0] === '=';
}
/** Strip the leading '=' (and any leading spaces) to get the formula body. */
static stripFormula(text: string): string {
return text.trimStart().slice(1);
}
/** Structural FormulaError detection — avoids importing the parser here. */
static isFormulaError(
value: FormulaLogic.CellValue
): value is { _error?: string; error?: string } {
return typeof value === 'object' && value !== null && ('_error' in value || 'error' in value);
}
/**
* Resolve a NON-formula literal to its value: '' → null (blank, SUMs as
* 0), a numeric string → a number, anything else → the text verbatim.
*/
static evalLiteral(text: string): FormulaLogic.CellValue {
const trimmed = text.trim();
if (trimmed.length === 0) return null;
const asNumber = Number(trimmed);
return !Number.isNaN(asNumber) && Number.isFinite(asNumber) ? asNumber : text;
}
/** Display string for a resolved value. */
static displayOf(value: FormulaLogic.CellValue): string {
if (value == null) return '·';
if (this.isFormulaError(value)) return String(value.error ?? value._error ?? '#ERR');
if (typeof value === 'number') {
return Number.isFinite(value)
? value.toLocaleString('en-US', { maximumFractionDigits: 2 })
: String(value);
}
if (typeof value === 'boolean') return value ? 'TRUE' : 'FALSE';
return String(value);
}
/** CSS class driven by error-ness, number sign, and whether it's a formula. */
static cssOf(value: FormulaLogic.CellValue, isFormula: boolean): string {
let base: string;
if (this.isFormulaError(value)) base = 'gc-err';
else if (value == null) base = 'gc-zero';
else if (typeof value === 'number')
base = value < 0 ? 'gc-neg' : value > 0 ? 'gc-pos' : 'gc-zero';
else base = 'gc-text';
return isFormula ? base + ' gc-formula' : base;
}
}
export namespace FormulaLogic {
export const $Class = Static($FormulaLogic); // anchor — statics live here
export let Class = $Class; // selection — a variant grid swaps this
/** A value a cell can resolve to. `FormulaError` is detected structurally. */
export type CellValue = number | string | boolean | null | { _error?: string; error?: string };
}ts
// FormulaGridExample.ts — the formula-grid route's state, in ivue. The
// MODEL (Sheet + FormulaCell + FormulaLogic) is the exact code the
// measured RESULTS.md numbers were produced with; this class is the page
// around it. `fast-formula-parser` loads via a dynamic import inside
// create(), so the route costs nothing until you build a sheet.
import { ref, shallowRef } from 'vue';
import { Reactive } from '../../ivue';
import { useRowWindow } from '../benchmarks/useRowWindow';
import { FormulaLogic } from './FormulaLogic';
import type { Sheet } from './Sheet';
class $FormulaGridExample {
// MUTABLE STATE — the sheet is replaced wholesale; shallowRef keeps a
// million cells out of the deep-proxy machinery.
get sheet() {
return shallowRef<Sheet.Model | null>(null);
}
get loading() {
return ref(false);
}
get creationMs() {
return ref(0);
}
get editing() {
return ref<{ r: number; c: number } | null>(null);
}
// re-trace deps after an edit (traceDeps is not reactive)
get depsBump() {
return ref(0);
}
// COMPOSABLE — the row window, hosted whole, created on first touch.
protected get $window() {
return useRowWindow({
rowCount: () => (this.sheet.value ? this.sheet.value.rows : 0),
rowHeight: this.Logic.ROW_HEIGHT,
viewportHeight: this.Logic.VIEWPORT_HEIGHT,
overscan: this.Logic.OVERSCAN
});
}
get window() {
return this.$window;
}
// TEMPLATE-REF TARGET — the scroll viewport; the SFC binds ref="scrollEl"
get scrollEl() {
return ref<HTMLElement | null>(null);
}
/** The pure-logic layer the page sizes and labels with. */
get Logic() {
return FormulaLogic.Class;
}
// DERIVED — plain getters; zero allocations per instance.
get columnCount() {
return this.Logic.COLS;
}
get smallRowCount() {
return this.Logic.ROWS;
}
get largeRowCount() {
return this.Logic.ROWS_1M;
}
get createLabel() {
return this.loading.value ? 'Loading parser…' : 'Create 100k cells';
}
get hasModel() {
return this.sheet.value !== null;
}
get modelCells() {
return this.sheet.value ? this.sheet.value.rows * this.columnCount : 0;
}
get modelCellsLabel() {
return this.modelCells.toLocaleString();
}
get viewportStyle() {
return { height: `${this.$window.totalHeight.value}px` };
}
get rowsStyle() {
return { transform: `translateY(${this.$window.offsetY.value}px)` };
}
get mountedCells() {
return this.$window.visibleRows.value.length * this.columnCount;
}
get mountedCellsLabel() {
return this.mountedCells.toLocaleString();
}
get creationLabel() {
return this.creationMs.value.toFixed(1);
}
get activeName() {
const active = this.editing.value;
return active ? this.a1(active.r, active.c) : 'fx';
}
get activeCell() {
const active = this.editing.value;
if (!active || !this.sheet.value) return null;
return this.sheet.value.cellAt(active.r + 1, active.c + 1) ?? null;
}
get activeDeps(): string[] {
void this.depsBump.value;
const active = this.editing.value;
const model = this.sheet.value;
if (!active || !model) return [];
return model
.traceDeps(active.r + 1, active.c + 1)
.map(([row, col]) => this.a1(row - 1, col - 1));
}
get activeDepsLabel() {
return this.activeDeps.join(', ');
}
get hasActiveDeps() {
return this.activeDeps.length > 0;
}
async create(rows: number) {
this.loading.value = true;
this.editing.value = null;
// The parser ships in its own lazy chunk; first click pays it once.
const { Sheet } = await import('./Sheet');
const start = performance.now();
const model = new Sheet.Class(rows, this.columnCount);
this.creationMs.value = performance.now() - start;
this.sheet.value = model;
this.loading.value = false;
}
createSmall() {
return this.create(this.smallRowCount);
}
createLarge() {
return this.create(this.largeRowCount);
}
columnLabel(columnIndex: number) {
return this.Logic.colLabel(columnIndex);
}
/** Header label for a 1-based `v-for="c in columnCount"` column. */
headerLabel(columnNumber: number) {
return this.columnLabel(columnNumber - 1);
}
/** The 1-based row number the gutter shows. */
rowNumber(row: number) {
return row + 1;
}
isEditing(row: number, col: number) {
return !!this.editing.value && this.editing.value.r === row && this.editing.value.c === col;
}
edit(row: number, col: number) {
this.editing.value = { r: row, c: col };
}
commitEdit() {
this.editing.value = null;
this.depsBump.value++;
}
/** The edit's blur commits — its own handler, so a subclass can treat a
* blur apart from an Enter. */
onEditBlur() {
this.commitEdit();
}
/** Enter in the edit commits. */
onEditEnter() {
this.commitEdit();
}
a1(row0: number, col0: number) {
return this.columnLabel(col0) + (row0 + 1);
}
}
export namespace FormulaGridExample {
export const $Class = $FormulaGridExample; // raw — children `extends` this
export let Class = Reactive($Class); // reactive — you `new` this
export type Instance = typeof Class.Instance; // defineExpose type & reactive() interop
}vue
<script setup lang="ts">
/**
* The formula grid, embedded live in the docs.
*
* The MODEL is imported from the playground's `formula-grid` example
* unchanged — `Sheet` (the one shared parser + O(1) cellAt), `FormulaCell`
* (ref-getter raw, ONE computed value, plain getters) and `FormulaLogic`
* are the exact files the measured RESULTS.md numbers were produced with,
* and the page state is the playground's own `FormulaGridExample` class.
* Only the docs chrome around them lives here: this SFC is wiring.
*
* `fast-formula-parser` (chevrotain-based, ~real bytes) is loaded via a
* DYNAMIC import inside the class's create(): `vitepress build` (SSR)
* never executes it and readers who don't click never download it.
* Nothing runs on mount.
*/
import DemoBox from '../DemoBox.vue';
import '@examples/benchmarks/grid.css';
import '@examples/formula-grid/formula.css';
import { FormulaGridExample } from '@examples/formula-grid/FormulaGridExample';
const grid = new FormulaGridExample.Class();
// the state destructure
const {
// state refs
sheet,
loading,
// element refs
scrollEl
} = grid;
</script>
<template>
<DemoBox
title="The formula grid — real formulas, live"
note="The model is the exact Sheet/FormulaCell code the measured numbers were produced with; the parser (fast-formula-parser, 280 Excel functions) loads on demand when you click. Live numbers are illustrative — the controlled gc-forced protocol lives in demo/formula/RESULTS.md."
>
<div class="d-row fg-controls">
<button class="d-btn primary" type="button" :disabled="loading" @click="grid.createSmall()">
{{ grid.createLabel }}
</button>
<button
class="d-btn"
type="button"
:disabled="loading"
title="40 columns × 25,000 rows. ~68 MB of model — fine on a desktop browser."
@click="grid.createLarge()"
>
Create 1M cells
</button>
<span v-if="grid.hasModel" class="d-mono">
{{ grid.modelCellsLabel }} cells · 52.5% live formulas · created in
{{ grid.creationLabel }} ms
</span>
</div>
<p v-if="!grid.hasModel" class="fg-hint">
Nothing built yet. Every cell in columns E–J (and every odd column beyond) holds a real
formula — <code>=A1+B1</code>, <code>=SUM(A1:D1)</code>, <code>=IF(A1>0,B1,C1)</code>, a
running sum — evaluated by a real parser, with the dependency graph discovered by Vue.
</p>
<template v-if="grid.hasModel">
<p class="fg-hint">
Click a cell to edit its formula or value. Try it: set
<strong>A1</strong> to <code>5000</code> and watch E1, G1, H1, I1 and the J column cascade.
Select <strong>I1</strong> and flip A1's sign — the tracked dependency set shifts branches.
</p>
<!-- fx bar: active cell's literal text + its LIVE tracked deps -->
<div class="fx-bar fg-fx">
<span class="fx-name">{{ grid.activeName }}</span>
<span v-if="grid.activeCell" class="fx-val">{{ grid.activeCell.raw.value }}</span>
<span v-else class="fx-empty">click a cell to see its formula</span>
<span v-if="grid.hasActiveDeps" class="fg-deps d-mono">
reads: {{ grid.activeDepsLabel }}
</span>
</div>
<div ref="scrollEl" class="gc-grid-scroll" @scroll="grid.window.onScroll">
<div class="gc-inner">
<div class="gc-head">
<div class="gc-rownum gc-head-cell">#</div>
<div v-for="column in grid.columnCount" :key="column" class="gc-cell gc-head-cell">
{{ grid.headerLabel(column) }}
</div>
</div>
<div class="gc-viewport" :style="grid.viewportStyle">
<div class="gc-rows" :style="grid.rowsStyle">
<div v-for="row in grid.window.visibleRows.value" :key="row" class="gc-row">
<div class="gc-rownum">{{ grid.rowNumber(row) }}</div>
<div
v-for="(cell, columnIndex) in sheet!.grid[row]"
:key="columnIndex"
class="gc-cell"
:class="cell.cssClass"
data-grid-cell
:data-row="row"
:data-col="columnIndex"
:title="cell.raw.value"
@click="grid.edit(row, columnIndex)"
>
<input
v-if="grid.isEditing(row, columnIndex)"
class="gc-edit"
v-model="cell.raw.value"
autofocus
@blur="grid.onEditBlur()"
@keyup.enter="grid.onEditEnter()"
/>
<template v-else>{{ cell.display }}</template>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="fg-mounted d-mono">
{{ grid.mountedCellsLabel }} DOM cells mounted (virtualized) out of
{{ grid.modelCellsLabel }} in the model — an unrendered formula cell never allocates its ref
or computed.
</div>
</template>
</DemoBox>
</template>
<style scoped>
.fg-controls {
margin-top: 0;
}
.fg-hint {
margin: 12px 0 0;
font-size: 0.86rem;
line-height: 1.55;
color: var(--vp-c-text-2);
}
.fg-hint code {
color: #a5b4fc;
font-size: 0.8rem;
}
.fg-hint strong {
color: #cbd5f0;
}
.fg-fx {
margin-top: 14px;
margin-bottom: 10px;
}
.fg-deps {
margin-left: auto;
color: #34d399 !important;
white-space: nowrap;
overflow: hidden;
text-overflow: ellipsis;
}
.fg-mounted {
margin-top: 8px;
font-size: 11px;
color: var(--vp-c-text-2);
}
</style>Open in StackBlitz ⚡ — the playground boots with this example's route and file active.
The measured heap/creation protocol lives in demo/formula/RESULTS.md; the benchmark context is on the Interactive Benchmarks page.