字典.md

字典的介绍

字典是一种以键值对形式存储数据的数据结构.字典的基础类是Array类,而不是Object类.

    function Dictionary(){
        this.datastore = new Array()
        this.add = add
        this.find =  find
        this.remove = remove
    }
    function add(key,value){
        this.datastore[key] = value
    }
    function find(key){
        return this.datastore[key]
    }
    this.remove(key){
        delete this.datastore[key]
    }

查询字典中的元素个数，需要定义一个count 方法。 length属性在这时是不起作用的，因为键的类型是字符串

    function count(){
        var count  = Object.keys(this.datastore).length
        return count
    }
    var nums = new Array()
    nums[0] = 1
    nums[1] = 2
    console.log(nums.length) // 2
    var checks =  new Array()
    checks['name'] = 'Bob'
    checks['age'] = '18'
    console.log(checks.length) // 0

clear方法,清空字典

    function clear(){
        for(var key of this.datastore){
            delete this.datastore[key]
        }
    }