jQuery将事件处理程序挂接到正在触发的对象的方法
jQuery hook up an event handler to an object's method being fired
var obj = { method: function(){alert("hello world"); }
$(obj).on("method", function(){ alert("the method was invoked"); });
$(obj).bind("method", function(){ alert("the method was invoked"); });
我正在尝试执行上述操作，但它似乎仅适用于用户事件，例如单击、鼠标悬停等。
我来自道场背景，您可以执行以下操作：
dojo.connect(obj, "method", function(){ alert("the method was invoked"); });
更具体地说，我正在尝试将事件处理程序绑定到在自定义 jQuery 小部件上调用的方法。
你可以
使用 jQuery 的$.proxy来做到这一点：
$(obj).on("eventName", $.proxy(obj.method, obj));
// or
$(obj).on("eventName", $.proxy(obj, "method")); // Note the quotes
如果你可以依赖 ECMAScript5 的特性（要么是因为你所有的目标浏览器都有 ES5，要么是因为你已经加载了 ES5 shim/shiv），你可以使用 Function#bind（因为它是一个支持填充码/shiv 的特性）：
$(obj).on("eventName", obj.method.bind(obj));
当然，在任何一种情况下，方法调用中的this将不再是您挂钩事件的元素（它将obj）。您应该接受方法中的 event 参数（例如，e ），然后使用 e.target（对于事件发起的元素）或e.delegateTarget（对于挂钩事件的元素，可能是 e.target 的祖先）。
这并不能完全回答我关于绑定到纯 JavaScript 对象的方法调用的原始问题，但我最终选择了：
_method: function(){
this.element.trigger("customEventName");
}
//...elsewhere
$("#WidgetNode").bind("customEventName", function(){ alert("invoked!"); });
而不是我最初尝试的：
_method: function(){
this.onMethodInvoked();
},
onMethodInvoked: function(){
//stub for listening
}
对于那些好奇道场如何做到这一点的人...
此代码允许您使用 dojo.connect 将处理程序连接到任何 javascript 对象上任何方法的调用
// this file courtesy of the TurboAjax Group, licensed under a Dojo CLA
// low-level delegation machinery
dojo._listener = {
// create a dispatcher function
getDispatcher: function(){
// following comments pulled out-of-line to prevent cloning them
// in the returned function.
// - indices (i) that are really in the array of listeners (ls) will
// not be in Array.prototype. This is the 'sparse array' trick
// that keeps us safe from libs that take liberties with built-in
// objects
// - listener is invoked with current scope (this)
return function(){
var ap=Array.prototype, c=arguments.callee, ls=c._listeners, t=c.target;
// return value comes from original target function
var r = t && t.apply(this, arguments);
// make local copy of listener array so it is immutable during processing
var lls;
//>>includeStart("connectRhino", kwArgs.profileProperties.hostenvType == "rhino");
if(!dojo.isRhino){
//>>includeEnd("connectRhino");
//>>includeStart("connectBrowser", kwArgs.profileProperties.hostenvType != "rhino");
lls = [].concat(ls);
//>>includeEnd("connectBrowser");
//>>includeStart("connectRhino", kwArgs.profileProperties.hostenvType == "rhino");
}else{
// FIXME: in Rhino, using concat on a sparse Array results in a dense Array.
// IOW, if an array A has elements [0, 2, 4], then under Rhino, "concat [].A"
// results in [0, 1, 2, 3, 4], where element 1 and 3 have value 'undefined'
// "A.slice(0)" has the same behavior.
lls = [];
for(var i in ls){
lls[i] = ls[i];
}
}
//>>includeEnd("connectRhino");
// invoke listeners after target function
for(var i in lls){
if(!(i in ap)){
lls[i].apply(this, arguments);
}
}
// return value comes from original target function
return r;
}
},
// add a listener to an object
add: function(/*Object*/ source, /*String*/ method, /*Function*/ listener){
// Whenever 'method' is invoked, 'listener' will have the same scope.
// Trying to supporting a context object for the listener led to
// complexity.
// Non trivial to provide 'once' functionality here
// because listener could be the result of a dojo.hitch call,
// in which case two references to the same hitch target would not
// be equivalent.
source = source || dojo.global;
// The source method is either null, a dispatcher, or some other function
var f = source[method];
// Ensure a dispatcher
if(!f||!f._listeners){
var d = dojo._listener.getDispatcher();
// original target function is special
d.target = f;
// dispatcher holds a list of listeners
d._listeners = [];
// redirect source to dispatcher
f = source[method] = d;
}
// The contract is that a handle is returned that can
// identify this listener for disconnect.
//
// The type of the handle is private. Here is it implemented as Integer.
// DOM event code has this same contract but handle is Function
// in non-IE browsers.
//
// We could have separate lists of before and after listeners.
return f._listeners.push(listener) ; /*Handle*/
},
// remove a listener from an object
remove: function(/*Object*/ source, /*String*/ method, /*Handle*/ handle){
var f = (source||dojo.global)[method];
// remember that handle is the index+1 (0 is not a valid handle)
if(f && f._listeners && handle--){
delete f._listeners[handle];
}
}
};
// Multiple delegation for arbitrary methods.
// This unit knows nothing about DOM,
// but we include DOM aware
// documentation and dontFix
// argument here to help the autodocs.
// Actual DOM aware code is in event.js.
dojo.connect = function(/*Object|null*/ obj,
/*String*/ event,
/*Object|null*/ context,
/*String|Function*/ method,
/*Boolean*/ dontFix){
// summary:
// Create a link that calls one function when another executes.
//
// description:
// Connects method to event, so that after event fires, method
// does too. All connected functions are passed the same arguments as
// the event function was initially called with. You may connect as
// many methods to event as needed.
//
// event must be a string. If obj is null, dojo.global is used.
//
// null arguments may simply be omitted.
//
// obj[event] can resolve to a function or undefined (null).
// If obj[event] is null, it is assigned a function.
//
// The return value is a handle that is needed to
// remove this connection with dojo.disconnect.
//
// obj:
// The source object for the event function.
// Defaults to dojo.global if null.
// If obj is a DOM node, the connection is delegated
// to the DOM event manager (unless dontFix is true).
//
// event:
// String name of the event function in obj.
// I.e. identifies a property obj[event].
//
// context:
// The object that method will receive as "this".
//
// If context is null and method is a function, then method
// inherits the context of event.
//
// If method is a string then context must be the source
// object object for method (context[method]). If context is null,
// dojo.global is used.
//
// method:
// A function reference, or name of a function in context.
// The function identified by method fires after event does.
// method receives the same arguments as the event.
// See context argument comments for information on method's scope.
//
// dontFix:
// If obj is a DOM node, set dontFix to true to prevent delegation
// of this connection to the DOM event manager.
//
// example:
// When obj.onchange(), do ui.update():
// | dojo.connect(obj, "onchange", ui, "update");
// | dojo.connect(obj, "onchange", ui, ui.update); // same
//
// example:
// Using return value for disconnect:
// | var link = dojo.connect(obj, "onchange", ui, "update");
// | ...
// | dojo.disconnect(link);
//
// example:
// When onglobalevent executes, watcher.handler is invoked:
// | dojo.connect(null, "onglobalevent", watcher, "handler");
//
// example:
// When ob.onCustomEvent executes, customEventHandler is invoked:
// | dojo.connect(ob, "onCustomEvent", null, "customEventHandler");
// | dojo.connect(ob, "onCustomEvent", "customEventHandler"); // same
//
// example:
// When ob.onCustomEvent executes, customEventHandler is invoked
// with the same scope (this):
// | dojo.connect(ob, "onCustomEvent", null, customEventHandler);
// | dojo.connect(ob, "onCustomEvent", customEventHandler); // same
//
// example:
// When globalEvent executes, globalHandler is invoked
// with the same scope (this):
// | dojo.connect(null, "globalEvent", null, globalHandler);
// | dojo.connect("globalEvent", globalHandler); // same
// normalize arguments
var a=arguments, args=[], i=0;
// if a[0] is a String, obj was ommited
args.push(dojo.isString(a[0]) ? null : a[i++], a[i++]);
// if the arg-after-next is a String or Function, context was NOT omitted
var a1 = a[i+1];
args.push(dojo.isString(a1)||dojo.isFunction(a1) ? a[i++] : null, a[i++]);
// absorb any additional arguments
for(var l=a.length; i<l; i++){ args.push(a[i]); }
// do the actual work
return dojo._connect.apply(this, args); /*Handle*/
}
// used by non-browser hostenvs. always overriden by event.js
dojo._connect = function(obj, event, context, method){
var l=dojo._listener, h=l.add(obj, event, dojo.hitch(context, method));
return [obj, event, h, l]; // Handle
}
dojo.disconnect = function(/*Handle*/ handle){
// summary:
// Remove a link created by dojo.connect.
// description:
// Removes the connection between event and the method referenced by handle.
// handle:
// the return value of the dojo.connect call that created the connection.
if(handle && handle[0] !== undefined){
dojo._disconnect.apply(this, handle);
// let's not keep this reference
delete handle[0];
}
}
dojo._disconnect = function(obj, event, handle, listener){
listener.remove(obj, event, handle);
}
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