purchase-let/node_modules/delegate/src/delegate.js

79 lines
2.1 KiB
JavaScript

var closest = require('./closest');
/**
* Delegates event to a selector.
*
* @param {Element} element
* @param {String} selector
* @param {String} type
* @param {Function} callback
* @param {Boolean} useCapture
* @return {Object}
*/
function _delegate(element, selector, type, callback, useCapture) {
var listenerFn = listener.apply(this, arguments);
element.addEventListener(type, listenerFn, useCapture);
return {
destroy: function() {
element.removeEventListener(type, listenerFn, useCapture);
}
}
}
/**
* Delegates event to a selector.
*
* @param {Element|String|Array} [elements]
* @param {String} selector
* @param {String} type
* @param {Function} callback
* @param {Boolean} useCapture
* @return {Object}
*/
function delegate(elements, selector, type, callback, useCapture) {
// Handle the regular Element usage
if (typeof elements.addEventListener === 'function') {
return _delegate.apply(null, arguments);
}
// Handle Element-less usage, it defaults to global delegation
if (typeof type === 'function') {
// Use `document` as the first parameter, then apply arguments
// This is a short way to .unshift `arguments` without running into deoptimizations
return _delegate.bind(null, document).apply(null, arguments);
}
// Handle Selector-based usage
if (typeof elements === 'string') {
elements = document.querySelectorAll(elements);
}
// Handle Array-like based usage
return Array.prototype.map.call(elements, function (element) {
return _delegate(element, selector, type, callback, useCapture);
});
}
/**
* Finds closest match and invokes callback.
*
* @param {Element} element
* @param {String} selector
* @param {String} type
* @param {Function} callback
* @return {Function}
*/
function listener(element, selector, type, callback) {
return function(e) {
e.delegateTarget = closest(e.target, selector);
if (e.delegateTarget) {
callback.call(element, e);
}
}
}
module.exports = delegate;