一个 js 循环变量的简单问题

<div id="box1">这里是第一个div</div>
<div id="box2">这里是第二个div</div>

function show(){
for (i=1; i<3; i++){
        var box= document.getElementById("mybox"+i);
        }
var text = box+i.innerHTML;
var newBox = document.createElement("div");
var btn = document.createElement("a");
        newBox.innerHTML = text.substring(0,200);
        btn.innerHTML = text.length > 200 ? "...显示全部" : "";
        btn.href = "###";
        btn.onclick = function(){
        if (btn.innerHTML == "...显示全部"){
                btn.innerHTML = "收起";
                newBox.innerHTML = text;
        }else{
        btn.innerHTML = "...显示全部";
        newBox.innerHTML = text.substring(0,200);
        }
}
        box.innerHTML = "";
        box.appendChild(newBox);
        box.appendChild(btn);
}
show();