jquery on 简易实现

        function delegate(parentSelectors, eventName, childSelectors, data, handler) {
            function each(arrlike, cb) {
                [].forEach.call(arrlike, cb)
            }
            var parents = document.querySelectorAll(parentSelectors)
            each(parents, function (parent) {

                // each(childs, function (child) {
                //     child.addEventListener(type, handler, false)
                // })
                parents.addEventListener(type, function (e) {
                    var childs = parent.querySelectorAll(childSelectors)
                    var target = e.target || e.srcElement
                    // target 本身为代理节点
                    // 或者 target 为代理节点子节点
                    if ([].includes.call(childs, target) || childs.contains(target)) {
                        // handler.call(target, e)
                    }

                }, false)
            })


        }

功能暂未实现

@萍2樱释ღ( ´･ᴗ･` )