为什么这个javascript无限循环？

Question

该方法constructBuilder()不应该是无限的,因为它被设置为仅循环10次并且data.length的值永远不会改变.

这个循环和方法实际上是完美的,直到我在循环中调用另一个方法.

当我getOptions(type)在这个循环中调用方法时,i变化的值非常奇怪,并且始终遵循以下模式:

1st run: i=0
2nd run: i=1
3rd run: i=3
4th run: i=5
5th run: i=6
6th run: i=4
7th run: i=4
8th run: i=4
nth run: i=4

i卡在4 的值,不增加,循环无限运行!

为什么会这样？

这是代码:

var data = [["Text Array", "Some more text", "btnText", "btn2text"],
            ["Text2", "2: more text", "btnText2", "btn2text2"],
            ...
           ];

var products, order;

function initialise() {
    products = loadProducts();
    order = new Order();
    constructBuilder();
}

function constructBuilder() {
    var qb_boxes_innerHTML = "";
    for (i=0; i<data.length; i++) {
      alert("i="+i + "; data length="+data.length);
      var box_innerHTML = "<table width=100% height=100% cellpadding=0; cellspacing=0; border=0>";
      box_innerHTML += "<tr><td width=100% height=\"50px\">" + data[i][0] + "</td></tr>";
      box_innerHTML += "<tr><td width=100% class=\"scroll\" valign=\"top\">" + data[i][1] + getOptions(i) + "</td></tr>";
      box_innerHTML += "<tr><td width=100% height=\"50px\" align=\"right\" valign=\"middle\"><form action=\"javascript:next();\"><input type=\"button\" value=\""
                    + data[i][2] + "\" onClick=\"prev();\"/><input id=\"continueBtn\" type=\"submit\" value=\""
                    + data[i][3] + "\" disabled/></form></td></tr>";
      box_innerHTML += "</table>";
      qb_boxes_innerHTML += "<div id=\"qb_box" + i + "\" class=\"qb_box\" style=\"visibility: hidden;\">" + box_innerHTML + "</div>";
    }
    document.getElementById("qb_boxes").innerHTML = qb_boxes_innerHTML;
    document.getElementById("qb_box0").style.visibility = "";
}
function getOptions(type) {
    var optionsList = getProducts(products, type);
    var options_html = "";
    for (i=0; i<optionsList.length; i++) {
      options_html += "<input id=\"check"+type+"_"+i+"\" type=\"checkbox\"/>" + optionsList[i].name + "<BR/>";
    }
    return options_html;
}

function getProducts(productList, type) {
      var productsOfType = new Array();
      for (i=0; i<productList.length; i++) {
        if (productList[i].type == type)
            productsOfType.push(productList[i]);
      }
      return productsOfType;
}

如果您需要更多信息,请发表评论.

谢谢你的期待.

Answer 1

通过使用i,var你实际上使用的是全局变量window.i.改变你的函数,以便i声明为局部变量:

function constructBuilder() {
    var qb_boxes_innerHTML = "";
    var i;
    /* ... */
}

Answer 2

您的i变量是全局变量,因此每个函数内的循环共享同一个计数器.使用循环声明()中的var关键字来声明局部变量.forfor(var i = 0; ...