为啥不管输入黑棋白棋，都是黑棋

window.onload=function(){

var chess=document.getElementById('chess');

var context=chess.getContext('2d');

context.strokeStyle="#BFBFBF"

drawChessBoard(context);

oneStep(1,1,true,context);

oneStep(2,1,false,context);

}

function drawChessBoard(cxt){

for(var i=0;i<15;i++){

cxt.moveTo(15+i*30,15);

cxt.lineTo(15+i*30,435);

cxt.stroke();

cxt.moveTo(15,15+i*30);

cxt.lineTo(435,15+i*30);

cxt.stroke();

}}

var oneStep=function(i,j,me,cxt){

cxt.beginPath();

cxt.arc(15+i*30,15+j*30,13,0,2*Math.PI);

cxt.closePath();

var gradient=cxt.createRadialGradient(15+i*30+2,15+j*30-2,15,15+i*30+2,15+j*30-2,0);

if (me=true){

gradient.addColorStop(0,"#0A0A0A");

gradient.addColorStop(1,"#636766");

}

else{

gradient.addColorStop(0,"#D1D1D1");

gradient.addColorStop(1,"#F9F9F9");

}

cxt.fillStyle=gradient;

cxt.fill ();

}