conway.js

function isAlive(state, x, y) {
    var count=0;
    for(var i=-1;i<=1;i++){
        for(var j=-1;j<=1;j++){
            if(!(j===0&&i===0)){
                var xIndex = (i+x+state.length)%(state.length);
                var yIndex = (j+y+state[xIndex].length)%(state[xIndex].length);
                if(state[xIndex][yIndex]){
                    count++;
                }
            }
        }
    }
    if(state[x][y]){
        if(count<2){
            return false;
        }
        else if(count<4){
            return true;
        }
        else{
            return false;
        }
    }
    else{
        if(count===3){
            return true;
        }
        else{
            return false;
        }
    }
}

function calcState(state){
    var newState=[]
    for(var x=0;x<state.length;x++){
        newState[x]=[]
        for(var y=0;y<state[x].length;y++){
            newState[x][y]=isAlive(state,x,y);
        }
    }
    return newState;
}


function init(evnt){
    var o=evnt.target;
    var doc=o.ownerDocument;
    var root=doc.documentElement;
    var width=parseInt(root.getAttribute("width"));
    var height=parseInt(root.getAttribute("height"));
    var xcells=50;
    var ycells=50;
    var state=[];
    var cells=[];

    function rectangle(x,y,width,height){
        var s = doc.createElementNS("http://www.w3.org/2000/svg","rect");
        s.setAttribute("x",x);
        s.setAttribute("y",y);
        s.setAttribute("width",width);
        s.setAttribute("height",height);
        s.setAttribute("stroke","#000");
        s.setAttribute("fill","none");
        return s;
    }

    for(x=0;x<xcells;x++){
        state[x]=[];
        cells[x]=[];
        for(y=0;y<ycells;y++){
            cells[x][y]=rectangle((x/xcells)*width,
                             (y/ycells)*height,
                             width/xcells,
                             height/ycells);
            if(Math.random()>0.5){
                state[x][y]=true;
                cells[x][y].setAttribute("fill","#000")
            }
            else{
                state[x][y]=false;
            }
        }
    }

    function loop(){
        state = calcState(state);
        for(x=0;x<xcells;x++){
            for(y=0;y<ycells;y++){
                if(state[x][y]){
                    cells[x][y].setAttribute("fill","#000");
                }
                else{
                    cells[x][y].setAttribute("fill","none");
                }
                root.appendChild(cells[x][y]);
            }
        }
        window.setTimeout(loop,15);
    }
    window.setTimeout(loop,0);
}