# 2020 / 3 / 17

function traverse(){
    var arr = []
    var elements = []

    if(document.all){
        elements = document.all
    }else{
        elements = document.getElementsByTagName('*')
    }

    for(var i = 0; i < elements.length; i++){
        var ele = elements[i]
        var width = parseFloat(ele.style.width) || ele.offsetWidth
        var height = parseFloat(ele.style.height) || ele.offsetWidth

        if(width > 50 && height > 50){
            arr.push(elements[i].tagName)
        }
    }

    return arr
}

# Demo

// Should equal 15
sum(1,2,3,4,5)
// Should equal 0
sum(5, null, -5)
// Should equal 9
sum('1.0', false, 1, true, 'A', 1, 'B', 1, 'C', 1, 'D', 1, 'E', 1, 'F', 1, 'G', 1)
// Should equal 0.3 not 0.30000000000004
sum(0.1, 0.2)

function sum(){
    var args = [].slice.call(arguments)
    return args.reduce((result, item) => {
        return result += parseFloat(item) || 0
    },0).toFixed(3) * 1000 / 1000
}

var arr = ['a','b','c','d','e']
var newArr = arr.splice(1,2,'newValue')

#   @desc:fibonacci
#   @params:count{Number}
#   @return:result{Number}

第count个fibonacci值，计数从0开始
fibonacci数列为：[1,1,2,3,5,8,13,21,34,...]

function getNthFibonacci(count){
    if(count <= 1) return 1

    return getNthFibonacci(count-1) + getNthFibonacci(count-2)
}

function obj(name){
    if(name){
        this.name = name
    }
}
obj.prototype.name = 'name2'
var a = obj('name1')
var b = new obj

Array.prototype.uniq = function(){
    // 长度为1，则直接返回当前的拷贝
    if(this.length <= 1) return this.slice(0)

    var result = []
    for(var i = 0; i < this.length; i++){
        // isExist判断是否已经存在，true存在，false不存在
        if(!isExist(result, this[i])){
            result.push(this[i])
        }
    }
    return result

    // 定义 isExist 函数
    function isExist(arr, item){
        if(arr.length === 0) return false

        var tmp

        for(var i = 0; i < arr.length; i++){
            tmp = arr[i]
            if(tmp === item){
                return true
            }

            // NaN 需要特殊处理
            if(!item && !tmp && tmp !== undefined && item !== undefined && isNaN(tmp) && isNaN(item)){
                return true
            }
        }

        return false
    }
}

function cloneDeep(obj){
    var buf;
    if(obj instanceof Array){
        buf = []  // 创建一个空的数组
        var i = obj.length
        while(i--){
            buf[i] = cloneDeep(obj[i])
        }
        return buf
    }else if(obj instanceof Object){
        buf = {}
        for(var k in obj){
            buf[k] = cloneDeep(obj[k])
        }
        return buf
    }else{
        return obj
    }
}

let eventListener = {
    // 页面加载完成后
    readyEvent:function(fn){
        if(fn == null){
            fn = document
        }
        var oldonload = window.onload
        if(typeof window.onload != 'function'){
            window.onload = fn
        }else{
            window.onload = function(){
                oldonload()
                fn()
            }
        }
    }

    // 绑定事件 ，参数：操作的元素，事件名称，事件处理函数
    addEvent:function(element, type, handler){
        if(element.addEventListener){
            // 参数：事件类型，事件处理函数，是否捕获
            element.addEventListener(type, handler, false)
        }else if(element.attachEvent){
            element.attachEvent('on'+type, function(){
                handler.call(element)
            })
        }else{
            element['on' + type] = handler
        }
    }


    // 移除事件
    removeEvent:function(element, type, handler){
        if(element.removeEventListener){
            element.removeEventListener(type, handler, false)
        }else if(element.detachEvent){
            element.detachEvent('on'+type, handler)
        }else{
            element['on' + type] = null
        }
    },

    // 阻止事件（主要是事件冒泡，因为Ie不支持事件捕获）
    stopPropagation:function(event){
        if(event.stopPropagation){
            event.stopPropagation()
        }else{
            event.cancelBubble = true
        }
    },

    // 取消事件的默认行为
    preventDefault:function(event){
        if(event.prevenrDefault){
            event.prevenrDefault()
        }else{
            event.returnValue = false
        }
    }
}