visit(callback, value)

Iterates cells in row-major order and calls callback({ row, col, value }) only for cells holding exactly value — matched by identity (===), the same story as strict search and the flood operations. Reading and mutating the grid inside the callback is allowed.

Example

(click to randomize q; every 🐸 cell gets highlighted)

code

Quadrille.cellLength = 50;
let q, hint;

function setup() {
  createCanvas(8 * Quadrille.cellLength, 8 * Quadrille.cellLength);
  q = createQuadrille(8, 8).rand(15, '🐸').rand(15, '🐯').rand(15, '🐮');
  highlight();
}

function draw() {
  background('#FADBD8');
  drawQuadrille(q);
  drawQuadrille(hint);
}

function mousePressed() {
  q.randomize();
  highlight();
}

function highlight() {
  hint = createQuadrille(8, 8);
  q.visit(({ row, col }) => hint.fill(row, col, color(0, 140)), '🐸');
}

The single value filter visits exactly the cells whose value === value.
Identity matters for objects: cells filled from one shared color('green') instance are all visited when filtering by that instance, while per-cell Quadrille.factory instances would each need their own filter. Strings, numbers, and emojis compare by value, so '🐸' just works.
Functions and Array/Set values can’t be single-value filters — they dispatch as predicate and collection filters instead.

Syntax

visit(callback, value)

Parameters

Param	Description
`callback`	Function called for each visited cell, receiving an object `{ row, col, value }`. Its return value is ignored
`value`	Any non-function, non-collection value: only cells holding exactly this value (`===`) are visited

visit(callback)visit(callback, collection)