チカチカ

noise.js

var SCREEN_SIZE = 500; //x 
var SIDE_CELLS = 200;
var CELL_SIZE = SCREEN_SIZE / SIDE_CELLS;
var FPS = 50; 
var canvas;
var context;

window.onload = function() {
    var field = new Array(SIDE_CELLS*SIDE_CELLS);

    canvas = document.getElementById('noise');
    canvas.width = canvas.height = SCREEN_SIZE;
    var scaleRate = Math.min(window.innerWidth/SCREEN_SIZE, window.innerWidth/SCREEN_SIZE); 
    canvas.style.height = canvas.style.width = SCREEN_SIZE*scaleRate+'px';
    context = canvas.getContext('2d');
    context.fillStyle = 'rgb(256,256,256)';

    update(field);
}

function update(field) {
    for (var s=0; s<field.length; s++) field[s] = Math.floor(Math.random()*2);
    drow(field);
    setTimeout(update, 1000/FPS, field);
}

function drow(field) {
    context.clearRect(0, 0, SCREEN_SIZE, SCREEN_SIZE);
    for (var i=0; i<field.length; i++) {
            if (field[i]) context.fillRect((i%SIDE_CELLS)*CELL_SIZE, Math.floor((i/SIDE_CELLS))*CELL_SIZE, CELL_SIZE, CELL_SIZE);
    }   
}