摘要：
在代码爬行的过程中，我遇到了一个奇怪的问题。您需要手动修改select的值，然后手动触发select的更改事件。但是，在网络上找到的trigger和onchange（）事件不会被触发，因此您别无选择，只能继续搜索。幸运的是，我在stackoverflow网站上看到了外国神的答案，并解决了遇到的问题。原始邮寄地址：http://stackoverflow.com/questions/2490825/how-to-t
在爬代码过程中，碰到一个稀奇古怪的问题。需要手工修改select的值，然后手动触发select的change事件，但使用网络上查到的通过trigger、onchange()事件触发都不执行，没办法，只好继续查找。
还好在stackoverflow网站上看到国外大神的回答，解决了碰到的问题。
原帖地址：http://stackoverflow.com/questions/2490825/how-to-trigger-event-in-javascript
手工触发的代码如下：
/** * Fire an event handler to the specified node. Event handlers can detect that the event was fired programatically * by testing for a 'synthetic=true' property on the event object * @param {HTMLNode} node The node to fire the event handler on. * @param {String} eventName The name of the event without the "on" (e.g., "focus") */ function fireEvent(node, eventName) { // Make sure we use the ownerDocument from the provided node to avoid cross-window problems var doc; if (node.ownerDocument) { doc = node.ownerDocument; } else if (node.nodeType == 9){ // the node may be the document itself, nodeType 9 = DOCUMENT_NODE doc = node; } else { throw new Error("Invalid node passed to fireEvent: " + node.id); } if (node.dispatchEvent) { // Gecko-style approach (now the standard) takes more work var eventClass = ""; // Different events have different event classes. // If this switch statement can't map an eventName to an eventClass, // the event firing is going to fail. switch (eventName) { case "click": // Dispatching of 'click' appears to not work correctly in Safari. Use 'mousedown' or 'mouseup' instead. case "mousedown": case "mouseup": eventClass = "MouseEvents"; break; case "focus": case "change": case "blur": case "select": eventClass = "HTMLEvents"; break; default: throw "fireEvent: Couldn't find an event class for event '" + eventName + "'."; break; } var event = doc.createEvent(eventClass); var bubbles = eventName == "change" ? false : true; event.initEvent(eventName, bubbles, true); // All events created as bubbling and cancelable. event.synthetic = true; // allow detection of synthetic events node.dispatchEvent(event, true); } else if (node.fireEvent) { // IE-old school style var event = doc.createEventObject(); event.synthetic = true; // allow detection of synthetic events node.fireEvent("on" + eventName, event); } };
html代码和调用如下
<a href="http://www.google.com" onclick="alert('clicked')" target="_blank">Go to google</a> <button>Trigger event</button> document.getElementsByTagName("button")[0].onclick = function() { fireEvent(document.getElementsByTagName("a")[0], "click"); }