js寫九九乘法表,基數行爲紅色字體,偶數行爲藍色字體

function foo(){
    for(var i=1;i<10;i++){
        for(var j=1;j<=i;j++){
            if(i%2==0){
		document.write("<span style='color:blue'>"+j+"*"+i+"="+j*i+"</span>"+"<span style='opacity:0'>*</span>");
	    }else{
                document.write("<span style='color:red'>"+j+"*"+i+"="+j*i+"</span>"+"<span style='opacity:0'>*</span>");
	        }
            }
	document.write("<br>");
	}
}
foo();