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delegate.js
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delegate.js
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'use strict';
var domEvents = require("../events");
var domData = require("../../data/data");
var domMatches = require("../../matches/matches");
var each = require("../../../js/each/each");
var isEmptyObject = require("../../../js/is-empty-object/is-empty-object");
var canCid = require("can-cid");
var dataName = "delegateEvents";
// Some events do not bubble, so delegating them requires registering the handler in the
// capturing phase.
// http://www.quirksmode.org/blog/archives/2008/04/delegating_the.html
var useCapture = function(eventType) {
return eventType === 'focus' || eventType === 'blur';
};
/**
* @module {events} can-util/dom/events/delegate/delegate delegateEvents
* @parent can-util/dom/events/events
*
* Add delegate listeners to DOM events. Delegated listeners use a selector on an
* ancestor element to determine when to fire the event for an item. This can help
* cases where large numbers of similar DOM nodes are added into a DOM subtree, since
* event handlers do not have to be attached to each new node.
*
* ```js
* var events = require("can-util/dom/events/events");
* require("can-util/dom/events/delegate/delegate");
* var el = document.createElement("div");
* var sub = document.createElement("div");
* sub.className = "foo"
* el.appendChild(sub);
*
* function delegateEventsHandler() {
* console.log("delegate event fired");
* }
*
* events.addDelegateListener.call(el, "click", ".foo", delegateEventsHandler, false);
*
* events.removeDelegateListener.call(el, "click", ".foo", delegateEventsHandler);
* ```
*/
var handleEvent = function (overrideEventType, ev) {
var events = domData.get.call(this, dataName);
var eventTypeEvents = events[overrideEventType || ev.type];
// contains the element and the handlers to call back
var matches = [];
if(eventTypeEvents) {
var selectorDelegates = [];
// convert eventTypeEvents from an object to
// an array.
each(eventTypeEvents, function(delegates){
selectorDelegates.push(delegates);
});
// walk from the target to the delegate element
// checking each selector
var cur = ev.target;
do {
selectorDelegates.forEach(function(delegates){
if (domMatches.call(cur, delegates[0].selector )) {
matches.push({
target: cur,
delegates: delegates
});
}
});
cur = cur.parentNode;
} while (cur && cur !== ev.currentTarget);
}
// make sure `cancelBubble` is set
var oldStopProp = ev.stopPropagation;
ev.stopPropagation = function() {
oldStopProp.apply(this, arguments);
this.cancelBubble = true;
};
for(var i = 0; i < matches.length; i++) {
var match = matches[i];
var delegates = match.delegates;
for(var d = 0, dLen = delegates.length; d < dLen; d++) {
if (delegates[d].handler.call(match.target, ev) === false) {
return false;
}
if (ev.cancelBubble) {
return;
}
}
}
};
/**
* @function can-util/dom/events/delegate/delegate.addDelegateListener events.addDelegateListener
* @parent can-util/dom/events/delegate/delegate
* @signature `events.addDelegateListener(eventType, selector, handler)`
* @param {String} eventType The type of the event to virtually bind to delegates
* @param {String} selector A CSS selector that matches all intended delegates
* @param {function(event)} handler The function to call when the event is dispatched
*
* Add an event as in [can-util/dom/events/events.addEventListener addEventListener] but with a selector
* matching child nodes ("delegates") for which the event should fire.
*
* Delegate events are limited to firing in the bubble phase.
*/
domEvents.addDelegateListener = function(eventType, selector, handler) {
var events = domData.get.call(this, dataName),
eventTypeEvents;
if (!events) {
domData.set.call(this, dataName, events = {});
}
// if the first of that event type, bind
if (!(eventTypeEvents = events[eventType])) {
eventTypeEvents = events[eventType] = {};
var delegateHandler = handleEvent.bind(this, eventType);
domData.set.call(this, canCid(handler), delegateHandler);
domEvents.addEventListener.call(this, eventType, delegateHandler, useCapture(eventType));
}
if (!eventTypeEvents[selector]) {
eventTypeEvents[selector] = [];
}
eventTypeEvents[selector].push({
handler: handler,
selector: selector
});
};
/**
* @function can-util/dom/events/delegate/delegate.removeDelegateListener events.removeDelegateListener
* @parent can-util/dom/events/delegate/delegate
* @signature `events.removeDelegateListener(eventType, selector, handler)`
* @param {String} eventType The type of the event to unbind
* @param {String} selector A CSS selector that matches a delegate selector added for this event type
* @param {function(event)} handler The function bound as handler when the listener was added
*
* Remove a delegated event added by in [can-util/dom/delegate/delegate.addDelegateListener addDelegateListener]
*/
domEvents.removeDelegateListener = function(eventType, selector, handler) {
var events = domData.get.call(this, dataName);
if (events && events[eventType] && events[eventType][selector]) {
var eventTypeEvents = events[eventType],
delegates = eventTypeEvents[selector],
i = 0;
// remove the matching eventType/selector/handler
while (i < delegates.length) {
if (delegates[i].handler === handler) {
delegates.splice(i, 1);
} else {
i++;
}
}
// if there are no more selectors, remove the selector
if(delegates.length === 0) {
delete eventTypeEvents[selector];
// if there are no more events for that eventType, unbind
if(isEmptyObject(eventTypeEvents)) {
var delegateHandler = domData.get.call(this, canCid(handler));
domEvents.removeEventListener.call(this, eventType, delegateHandler, useCapture(eventType));
delete events[eventType];
if(isEmptyObject(events)) {
domData.clean.call(this, dataName);
}
}
}
}
};