当此跨度值更改时，如何触发事件？

Question

我正在尝试在当前页面的股票价格发生变化时获取控制台日志。

页数： https://www.google.com/finance?q=NASDAQ%3AGOOG&ei=yvbRVbHSCcKgmAGyu7CoDA

元素 ID： #price-panel > div > span > span

尝试 1：失败

$("#price-panel div span span").onchange = function() { console.log('change')}

尝试 2： 失败

document.getElementById('price-panel').children[0].children[0].onchange = function() { console.log('change')}

builtwith.com 表示 javascript 是 "google api"，它与 google 搜索不明确，因此没有太大帮助。

我可以查看什么事件来了解此元素何时更改？

Answer 1

span 元素没有 onchange 事件。你可以做的一件事是引入一个循环来定期检查当前内容和以前持有的内容，如果两者不同就做一些事情：

var content = null,
    $element = $("#price-panel div span span");

setInterval(function() {
    var currentText = $element.text();

    if (currentText != content) {
        // A change has happened
        console.log("Change");
        content = currentText;
    }
}, 30000 /* check every 30 seconds */);

Answer 2

来自 Dom Events as your try to listen to text changes in <span> you may be able to use DOMCharacterDataModified.

或者您可以使用 MutationObserver 来捕获更改。

var span = document.querySelector('#test');
var text = document.createTextNode('tttt');

// This may be deprecated.
span.addEventListener('DOMCharacterDataModified', function() {
    alert('span text changed to: ' + this.innerHTML);
});

// You may use MutationObserver instead.
var mutateObserver = new MutationObserver(function(records) {
  console.log(records);
});
mutateObserver.observe(span, {
  childList: true,                                 // capture child add/remove on target element.
  characterData: true,                     // capture text changes on target element
  subtree: true,                                   // capture childs changes too
  characterDataOldValue: true  // keep of prev value
});

setTimeout(function() {
  span.innerHTML ='SSSS';
}, 2000);

setTimeout(function() {
  span.appendChild(text);
}, 3000);

setTimeout(function() {
  text.data = '3123';
}, 4000);

<span id="test">This is a span</span>

当此跨度值更改时，如何触发事件？

How can I trigger an event when this span value changes?

html

javascript

jquery

google-finance