一、Frequency Number处理前准备

Git准备
- 通过连接https://git-for-windows.github.io下载Windows版本git并安装
- 安装后打开GitBash，通过命令npm install安装nmp包。
- 通过命令npm install -g jasmine安装jasmine测试框架
- 初步练习创建版本库，并熟悉相关命令如git init、git add、git status、git commit -m、git log、git log --pretty=oneline、git checkout、git reset。
  git简介.png
Nodejs准备
- 通过连接https://nodejs.org/dist/v4.4.3/node-v4.4.3-x64.msi下载64Windows版本的Nodejs并安装。
- 熟悉命令npm init、npm install的使用
  Nodejs简介 .png

二、Frequency Number要求

nodejs小程序：
- 处理一段字符串信息，这段字符串信息是由英文单词组成，每两个单词之间有空格；
- 处理结果也为一段字符串，这个字符串应该每行只显示一个单词和它的数量，并且按出现频率倒序排列。
example:
- input:
  “it was the age of wisdom it was the age of foolishness it is”
- output:
```
was 2
the 2
age 2
of 2 
wisdom 1
foolishness 1
is 1```
```

三、Frequency Number处理过程

任务划分

思路.png

主函数main

var format = function (word,count){
    return word +" "+ count;
};
var group = function(wordArray){
    return wordArray.reduce((array,word) => {
            var entry = array.find((e) =>e.word ===word);
    if(entry){
        entry.count++;
    }else{
        array.push({word:word,count:1});
    }
    return array;
},[]);
};
var split = function(words){
    return words.split(/\s+/);
};
var sort = function(groupedWords){
    groupedWords.sort((s,y)=>y.count - x.count);
};
function main(words){
    if(words!== ''){
        var wordArray = words.split(/\s+/);
        var groupedWords = group(wordArray);
        groupedWords.sort((x,y) =>y.count -x.count);
        return groupedWords.map((e) => format(e.word,e.count)).join('\r\n');
    }
    return '';
}
module.exports = main;

测试代码test

var main = require("./main.js");
describe("Word Frequency",function(){
    it("test1  returns empty string given empty string",function(){
        var result = main('');
        expect(result).toEqual('');
    });
    it("test2  returns string given one word",function(){
        var result = main('he');
        expect(result).toEqual('he 1');
    });
    it("test3  returns string given two different words",function(){
        var result = main('he is');
        expect(result).toEqual('he 1\r\nis 1');
    });
    it("test4  returns string given duplicated words",function(){
        var result = main('he is he');
        expect(result).toEqual('he 2\r\nis 1');
    });
    it("test5  returns string given duplicated words need to be sorted",function(){
        var result = main('he is is');
        expect(result).toEqual('is 2\r\nhe 1');
    });
    it("test6  returns string given words splited by multiple spaces",function(){
        var result = main('he is');
        expect(result).toEqual('he 1\r\nis 1');
    });
    it("test7  returns string given words splited by multiple spaces",function(){
        var result = main('it was the age of wisdom it was the age of foolishness it is');
        expect(result).toEqual('it 3\r\nwas 2\r\nthe 2\r\nage 2\r\nof 2\r\nwisdom 1\r\nfoolishness 1\r\nis 1');
    });
});