25.迭代器模式

var Iterator = function(items, container) {
        var container = contaner || document.getElementById(container) || document
        var items = container.getElementByTagName(items)
        var length = items.length, index = 0
        var splice = [].splice
        return {
            first: function() {
                index = 0
                return items.index[0]
            },
            next: function() {
                if(++index < length) {
                    return item[index]
                } else {
                    index = length -1
                    return null
                }
            },
            get: function(num) {
                index = num > 0 ? num % length : num % length +length;
                return items[index]
            },
            dealEach: function(fun) {
                var args = Array.prototype.slice(arguments, 1)
                for (let index = 0; index < length; index++) {
                    fun.apply(item[i], args)

                }
            },
            dealItem: function(num, fun) {
                fun.apply(this.get(num), Array.prototype.slice(arguments, 2))
            },
            exclusive: function(num, allFun, numFun) {
                this.dealEach(allFun)
                if(Object.prototype.toString.call(num) === '[object Array]') {
                    for(var i = 0, len = num.length; i < len; i++) {
                        this.dealItem(num[i], numFun)
                    } 
                } else {
                    this.dealItem(num, numFun)
                }
            },
        }
    }
    // 数组迭代器
    var ArrayIterator = function(arr, fun) {
        for(var i = 0; i< arr.length; i++) {
            if(fun.call(arr[i], i, arr[i]) === false) {
                break;
            }
            // fun.apply(i,arr[i])
        }
    }
    var eachObject = function(obj, fun) {
        for(var i in obj) {
            if(fun.call(obj[i], i , obj[i]) === false) {
                break;
            }
        }
    }
    var A = {
        client: {
            user: {
                name: 'guohua'
            }
        }
    }
    function Agetter(key) { 
        if(!A) return undefined
        var result = A
        var key = key.split('.')
        for (let index = 0; index < key.length; index++) {
            const element = key[index];
            if(result[element] !== 'undefined') {
                result = result[element]
            } else {
                return undefined
            }
        }
        return result
    }
    console.log(Agetter('client.user.name'))