相关疑难解决方法(0)

来自Mozilla的简要改变片段在JavaScript中使用XPath的介绍正在抛出异常.

[Exception... "An attempt was made to use an object that is not, or is no longer, usable" code: "11" nsresult: "0x8053000b (InvalidStateError)" location: "debugger eval code Line: 6"]

码:

var headings = document.evaluate('//h2', document, null, XPathResult.ANY_TYPE, null );
var thisHeading = headings.iterateNext();

while (thisHeading) {
  thisHeading.textContent = '\n';
  thisHeading = headings.iterateNext();
}

与原始代码的区别在于我正在改变元素 - 而不仅仅是阅读它们.

为什么我会看到异常以及如何在迭代中更改元素？