can/util/bind/bind.js

MIT-licensed, client-side, JavaScript framework that makes building rich web applications easy.

steal('can/util', function (can) {
	/**
	 * @typedef {{bind:function():*,unbind:function():*}} can.util.bind
	 *
	 * Provides mixin-able bind and unbind methods. `bind()` calls `this._bindsetup`
	 * when the first bind happens and.  `unbind()` calls `this._bindteardown` when there
	 * are no more event handlers.
	 *
	 */
		// ## Bind helpers
	can.bindAndSetup = function () {
		// Add the event to this object
		can.addEvent.apply(this, arguments);
		// If not initializing, and the first binding
		// call bindsetup if the function exists.
		if (!this.__inSetup) {
			if (!this._bindings) {
				this._bindings = 1;
				// setup live-binding
				if (this._bindsetup) {
					this._bindsetup();
				}
			} else {
				this._bindings++;
			}
		}
		return this;
	};
	can.unbindAndTeardown = function (event, handler) {
		if (!this.__bindEvents) {
			return this;
		}

		var handlers = this.__bindEvents[event] || [];
		var handlerCount = handlers.length;

		// Remove the event handler
		can.removeEvent.apply(this, arguments);
		if (this._bindings === null) {
			this._bindings = 0;
		} else {
			// Subtract the difference in the number of handlers bound to this
			// event before/after removeEvent
			this._bindings = this._bindings - (handlerCount - handlers.length);
		}
		// If there are no longer any bindings and
		// there is a bindteardown method, call it.
		if (!this._bindings && this._bindteardown) {
			this._bindteardown();
		}
		return this;
	};
	return can;
});