实用地测试特定事件处理程序(函数)是否使用jQuery绑定到对象的事件 [英] Pragmatically test if specific event handler(function) is bound to an object's event using jQuery

问题描述

我正在寻找一种方法来专门测试特定事件是否将某个处理程序(函数)绑定到特定对象.

I was looking for method to specifically test if a certain handler(function) was bound to specific object on a specific event.

我要解决的问题是我想将处理程序绑定到对象卸载事件，但是我想要一种方法来测试它是否已经绑定，因此我没有两次绑定它.

The problem I am trying to solve is I want to bind a handler to an objects unload event but I wanted a way to test if it was already bound so I did not bind it twice.

推荐答案

以下是对我有用的解决方案.我使用了这个stackoverflow答案( https://stackoverflow.com/a/2518441/2512022 )创建以下函数来测试对象是否具有绑定到特定事件的特定处理程序.

Here is a solution that worked for me. I used this stackoverflow answer (https://stackoverflow.com/a/2518441/2512022) to create the following function to test if a object has a specific handler bound to a specific event.

此函数将对象，事件名称和处理程序函数名称作为输入参数，如果该函数绑定了传入对象上的事件，则将返回true/false.

This function take a Object, Event Name, and handler function name as input parameters and will return true/false if the function is bound the event on the object passed in.

function testHandler(obj, sEvent, sHandlerName)
{
    var retVal = false;

    // Get all events bound to object
    var windowEvents = jQ._data(obj, "events");

    // Get all handlers for a specific event
    var handlers = windowEvents[sEvent];

    jQ(handlers).each(function() {
        // Using passed name to see if there is a match
        if(this.handler.name === sHandlerName)
        {
            retVal = true;
            return;
        }
    });

    return retVal;
}

然后按如下所示调用函数.

Then call the function as follows.

// Test if there is a beforeclose() handler bound to the window objects
// "beforeunload" event

testHandler(window, "beforeunload", "beforeclose");

您甚至可以测试事件是否附加了匿名处理程序.在此"下方的调用中引用了一个按钮，我们正在测试按钮单击事件是否附加了匿名处理

You could even test if there is on anonymous handler attached to an event. In the call below "this" references a button, and we are testing if there is an anonymous hanlder attached to the buttons click event

testHandler(this, "click", "anonymous");

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