不更新模态主体

I have an empty modal on my page and I'm performing an ajax call as below (simplified for reading)

function returnIt(x)
{
    $.ajax({
    type:"POST",
    url:"link",
    data:{id:"123"},
    success: function(data)
        {
        data=JSON.parse(data);
        var content=document.getElementById("returnItModalBody").innerHTML;
        for(var i=0;i<data.length;i++)
            {
            if(data[i]["nick"]==1)
               content+="<p>"+data[i]["upd"]+"</p>";
            else
               content+="<p>"+data[i]["upd"]+"</p>";
            }
        alert(content);
        $("#returnItModal").modal('show');
        }
     });
}

When I tell the script to alert with content it shows it should show in modal. When modal opens, there is nothing in its body.

What am I missing here?

Thanks

var content=document.getElementById("returnItModalBody").innerHTML;

That copies the value of innerHTML (a string) to content.

content+="<p>"+data[i]["upd"]+"</p>";

Then you assign a new string to content

alert(content)

Then you look at the string in content

You never change innerHTML.

If you want to change innerHTML then you have to assign a new value to it.