HTML5でキャンバスをクリアする方法は何ですか

function clearCanvas<span style="font-family: Verdana, Arial, 宋体;">()</span> 
{ 
    var c=document.getElementById("myCanvas"); 
    var cxt=c.getContext("2d"); 
    c.height=c.height; 
}

function clearCanvas() 
{ 
    var c=document.getElementById("myCanvas"); 
    var cxt=c.getContext("2d"); 
    cxt.clearRect(0,0,c.width,c.height); 
}

function clearCanvas() 
{ 
    var c=document.getElementById("myCanvas"); 
    var cxt=c.getContext("2d"); 
       
    cxt.fillStyle="#000000"; 
    cxt.beginPath(); 
    cxt.fillRect(0,0,c.width,c.height); 
    cxt.closePath(); 
}