字典

一直以键值对形式存储的数据结构 与Javascript 的object 很相近

Dictionary 类实现

    function Dictionary() {
        this.dataStore = []
    }
    Dictionary.prototype = {
        add: function(key, value) {
            this.dataStore[key] = value
        },
        find: function(key) {
            return this.dataStore[key] || 'no exist'
        },
        remove: function(key) {
            delete this.dataStore[key]
        },
        show: function() {
            return this.dataStore
        }
    }

    var eg = new Dictionary()
    eg.add('name', 'guohua')
    eg.add('age', 10)

Dictionary类的辅助方法

length: function () {
    return Object.keys(this.dataStore).length
    // 之所以不直接返回 this.dataStore.length 是因为当数组的key是字符串时不会计算长度
    /*
    var pbook = []
    pbook['David'] = 2
    pbook['Jennifer'] =1
    此时的pbook.length = 0
    */
},
clear: function() {
    for(var k of Object.keys(this.dataStore)) {
        console.log(k)
        delete this.dataStore[k]
    }
},
sort: function() {
    var sortStore = []
    Object.keys(this.dataStore).sort().forEach(item => {
        sortStore[item] = this.dataStore[item]
    })
    return sortStore
}

完整代码

function Dictionary() {
        this.dataStore = []
    }
    Dictionary.prototype = {
        add: function (key, value) {
            this.dataStore[key] = value
        },
        find: function (key) {
            return this.dataStore[key] || false
        },
        remove: function (key) {
            delete this.dataStore[key]
        },
        show: function () {
            return this.dataStore
        },
        length: function () {
            return Object.keys(this.dataStore).length
            // 之所以不直接返回 this.dataStore.length 是因为当数组的key是字符串时不会计算长度
            /*
            var pbook = []
            pbook['David'] = 2
            pbook['Jennifer'] =1
            此时的pbook.length = 0
            */
        },
        clear: function() {
            for(var k of Object.keys(this.dataStore)) {
                console.log(k)
                delete this.dataStore[k]
            }
        },
        sort: function() {
            var sortStore = []
            Object.keys(this.dataStore).sort().forEach(item => {
                sortStore[item] = this.dataStore[item]
            })
            return sortStore
        }
    }

    var eg = new Dictionary()
    eg.add('name', 'guohua')
    eg.add('age', 10)

    /* 显示一段文字中 单词重复的次数  
    * 'the brown fox jumped over the blue fox' 
    * ['the':2, 'brown':1, 'fox':2, 'jumped': 1, 'over': 1, 'blue': 1]
    */
    var words = new Dictionary()
    var text = 'the brown fox jumped over the blue fox' 
    text.split(' ').forEach(item => {
        if(words.find(item)) {
            words.add(item,  words.find(item) + 1)
        } else {
            words.add(item, 1)
        }
    })