Question

The logged value is shown below:

but why when I use document.write or alert it’s a blank variable.

here’s the code:

$("#subTile").click(function(){
            var c=[[],[],[]];//content
            $(".col").each(function(){
                var r=$(this).attr("rel");
                r--;
                $(this).find(".bulk").each(function(i){
                    var t=$(this).find("input:eq(0)").val();//title
                    var img=$(this).find("input:eq(1)").val();//img url
                    var content=$(this).find("textarea").val();
                    if(t!=="")
                    {
                        c[r][i]=[];
                        c[r][i]["title"]=t;
                        c[r][i]["img"]=img;
                        c[r][i]["content"]=content;
                    }
                })
            });
            console.log(c);
            document.write(c);

Answer 1

because document.write is converting c into its string representation.
you can use:

for (var i=0; i<c.length; i++) {
  document.write("Element " +i+ " contains: " +c[i]+ "<br />");
}