数据结构与算法JavaScript描述练习------第2章数组-CSDN博客

本文链接：https://blog.csdn.net/maxiumII/article/details/142826387

0.练习环境为：microEdge浏览器，控制台为：浏览器按F12。

先新建一个简单的HTML网页，1.html：

<!doctype html>
<html lang="en">
	<head>
		<title>Dog</title>
		<meta charset="utf-8">
	</head>
	<body>
		<script src = "1.js"></script>
	</body>
</html>

再新建一个1.js文件，作以下练习（保存到1.js）。

打开1.html，在浏览器F12的JavaScript控制台查看输出。

想深入知道为什么，先看深入浅出HTML与CSS，深入浅出HTML5编程，深入浅出JavaScript语言等书籍，这几天花了时间把这三本书草草看了一遍，大概有些印象。

1. 创建一个记录学生成绩的对象，提供一个添加成绩的方法，以及一个显示学生平均成绩的方法。

function Student() {
    this.scores = [];
	this.addScore = addScore;
	this.displayAverage = displayAverage;
}

function addScore(score) {
    this.scores.push(score);
}

function displayAverage() {
	var total = 0;
    var average = 0;
	if (this.scores.length === 0) {
		average = 0;
	} else {
		total = this.scores.reduce((acc, score) => acc + score);
		average = total / this.scores.length;
	}
    console.log("平均成绩是：" + average.toFixed(2));
}

const student1 = new Student();
student1.addScore(85);
student1.addScore(90);
student1.addScore(88);
student1.displayAverage();

2. 将一组单词存储在一个数组中，并按正序和倒序分别显示这些单词。

var words = ["apple", "banana", "cherry", "date", "elderberry", "fig", "grape", "honeydew", "indigo", "jelly"];

console.log("正序显示单词：");
words.forEach(word => console.log(word));

console.log("\n倒序显示单词：");
words.reverse().forEach(word => console.log(word));

3. 修改本章前面出现过的 weeklyTemps 对象，使它可以使用一个二维数组来存储每月的有用数据。增加一些方法用以显示月平均数、具体某一周平均数和所有周的平均数。

function weekTemps() {
	this.dataStore = [];
	this.addWeeklyTemps = addWeeklyTemps;
	this.weeklyAverage = weeklyAverage;
	this.monthlyAverage = monthlyAverage;
	this.overallAverage = overallAverage;
}

function addWeeklyTemps(month, weeklyTemps) {
	if (!this.dataStore[month]) {
		this.dataStore[month] = [];
	}
	this.dataStore[month].push(weeklyTemps);
};

function monthlyAverage(month) {
	if (!this.dataStore[month] || this.dataStore[month].length === 0) {
		return 0; 
	}
	var total = 0;
	var count = 0;
	for (var i = 0; i < this.dataStore[month].length; i++) {
		total += this.weeklyAverage(month, i);
		count++;
	}
	return total / count;
};

function weeklyAverage(month, weekIndex) {
	if (!this.dataStore[month] || !this.dataStore[month][weekIndex]) {
		return 0; 
	}
	var total = 0;
	for (var i = 0; i < this.dataStore[month][weekIndex].length; i++) {
		total += this.dataStore[month][weekIndex][i];
	}
	return total / this.dataStore[month][weekIndex].length;
};

function overallAverage() {
	var total = 0;
	var count = 0;
	for (var month in this.dataStore) {
		for (var i = 0; i < this.dataStore[month].length; i++) {
			for (var j = 0; j < this.dataStore[month][i].length; j++) {
				total += this.dataStore[month][i][j];
				count++;
			}
		}
	}
	return total / count;
};


var thisWeek = new weekTemps();
thisWeek.addWeeklyTemps(0, [52, 55, 61, 65, 55, 50, 52, 49]); 
thisWeek.addWeeklyTemps(0, [53, 56, 62, 66, 56, 51, 53, 50]); 
thisWeek.addWeeklyTemps(1, [54, 57, 63, 67, 57, 52, 54, 51]); 

console.log("第一个月的平均温度：", thisWeek.monthlyAverage(0)); 
console.log("第二个月的平均温度：", thisWeek.monthlyAverage(1)); 

console.log("第一个月第一周的平均温度：", thisWeek.weeklyAverage(0, 0));
console.log("第一个月第二周的平均温度：", thisWeek.weeklyAverage(0, 1));

console.log("所有周的平均温度：", thisWeek.overallAverage());

4. 创建这样一个对象，它将字母存储在一个数组中，并且用一个方法可以将字母连在一起，显示成一个单词。

function LetterStorage() {
	this.letters = [];
	this.addLetter = addLetter;
	this.joinLetters = joinLetters;
}
function addLetter(letter) {
	this.letters.push(letter);
}
function joinLetters() {
	return this.letters.join("");
}

var wordBuilder = new LetterStorage();
wordBuilder.addLetter('H');
wordBuilder.addLetter('e');
wordBuilder.addLetter('l');
wordBuilder.addLetter('l');
wordBuilder.addLetter('o');
console.log(wordBuilder.joinLetters());