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[Java教程]手动触发dom节点事件代码


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");}