动态生成表格 - javascript

浏览数：19 / 时间：2015年06月08日

一、JSON数据源

    JSON解释：

JSON是一种取代XML的数据结构,和xml相比,它更小巧但描述能力却不差,由于它的小巧所以网络传输数据将减少更多流量从而加快速度,

那么,JSON到底是什么?

JSON就是一串字符串 只不过元素会使用特定的符号标注。

{} 双括号表示对象

[] 中括号表示数组

"" 双引号内是属性或值

: 冒号表示后者是前者的值(这个值可以是字符串、数字、也可以是另一个数组或对象)

所以 {"name": "Michael"} 可以理解为是一个包含name为Michael的对象

而[{"name": "Michael"},{"name": "Jerry"}]就表示包含两个对象的数组

当然了,你也可以使用{"name":["Michael","Jerry"]}来简化上面一部,这是一个拥有一个name数组的对象
    详细介绍请参见W3SCHOOL: http://www.w3school.com.cn/json/

    JSON规范：http://www.ecma-international.org/ecma-262/5.1/

1.1 students


		var students = [
			{"cName": "class 1", "ID": "1001", "name": "李X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1002", "name": "张X威", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1003", "name": "于X洋", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1004", "name": "张X扬", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1005", "name": "周X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1006", "name": "王X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1007", "name": "李X朋", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1008", "name": "邬X春", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 5", "ID": "1009", "name": "李X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 5", "ID": "1010", "name": "孙X丽", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]}
		];


二、函数设计

      所谓的动态就是使用删表和写表的操作。

2.1 删除表格

       删除除了表头之外的数据。

CourseInf.deleteTable = function (table) {
	var mBody = table.getElementsByTagName('tbody'); 
	
	var len = table.rows.length;
	
	for (var i = 1; i < len; i++) {
		table.removeChild(mBody[1]);
	}
};

2.2 写表格

CourseInf.writeTable = function (obj, table) {
	var array = [];
	var className = obj.value;
	
	var iAcc = 0;
	var rowNum = 0;
	var str = "";
	
	for (var i = 0; i < CourseInf.gradeArrays.length; i++) {

		for (var key in CourseInf.gradeArrays[i]) {
			if (CourseInf.gradeArrays[i][key] == className){
				CourseInf.flag = true;
				rowNum++;
			}
			else {	
				if (CourseInf.flag) {
					array[key] = CourseInf.gradeArrays[i][key];
				}
			}

		}
		CourseInf.flag = false;		
		
		if (rowNum != 0) {
			for (var j in array) {
				str = array[j];
				CourseInf.classArrays[iAcc] = str;
				
				iAcc++;
			}
			CourseInf.insertTable(4, 1, CourseInf.classArrays, table);
			
		}
		
		rowNum = 0;		
	}
	
	CourseInf.iCount = 0;
};
    如果数组中某个键值（cName）等于className则执行：标志为真；并且行数+1操作。

    否则，判断标志是否为真？为真读取数据。

			if (CourseInf.gradeArrays[i][key] == className){
				CourseInf.flag = true;
				rowNum++;
			}
			else {	
				if (CourseInf.flag) {
					array[key] = CourseInf.gradeArrays[i][key];
				}
			}

    行数不等于0时，插入表格数据

CourseInf.insertTable = function (colNum, rowNum, array, table) {
	var mBody = document.createElement("tbody");
	
	for (var i = 0; i < rowNum; i++) {
		var mTr = document.createElement("tr");
		
		var j = 0;
		for (j = 0; j < colNum; j++) {
			var mCell = document.createElement("td");
			var mText = document.createTextNode(array[j + CourseInf.iCount]);
			
			mCell.appendChild(mText);
			mTr.appendChild(mCell);
		}
		CourseInf.iCount += j;
		mBody.appendChild(mTr);
	}
	table.appendChild(mBody);
};

2.3 删除重复项

    我们在读取班级列表的时候，希望一个班级只能出现一次。

    所以，我们要处理多个“class 1”和“class 5”的问题。

	for (var i = 0; i < array.length; i++) {
		obj[array[i]] = true;
	}
    obj[array[i]] = true;

    也许这么看就容易懂了obj[key] = true;


附：

    dynamicTable.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
	<title>动态创建表格</title>
	<script type="text/javascript">
		var students = [
			{"cName": "class 1", "ID": "1001", "name": "李X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1002", "name": "张X威", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1003", "name": "于X洋", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1004", "name": "张X扬", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1005", "name": "周X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1006", "name": "王X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1007", "name": "李X朋", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 1", "ID": "1008", "name": "邬X春", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 5", "ID": "1009", "name": "李X", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]},
			{"cName": "class 5", "ID": "1010", "name": "孙X丽", "course": ["英语", "高数"], "elective": ["政治经济学", "哲学"]}
		];
	</script>
	
	<script type="text/javascript" src="dynamicTable.js" ></script>
	
	</head>

	<body onLoad="CourseInf.loadData(students)">
		<select id="className" onChange="CourseInf.readClasses(this)">
		</select>
		<br>     
		<table id="tb1" border="1">
		  <tr>
		    <th>学号</th>
		    <th>姓名</th>
		    <th>必修课</th>
		    <th>选修课</th>
		  </tr>
		</table>
	
	</body>
</html>

    dynamicTable.js

/*
 * 课程信息
 * @author xiaobin
 */

var CourseInf = {
	gradeArrays :   [],
	classArrays :	[],
	
	iCount 		:	0,
	flag 		: 	false,
};	


CourseInf.deleteTable = function (table) {
	var mBody = table.getElementsByTagName('tbody'); 
	
	var len = table.rows.length;
	
	for (var i = 1; i < len; i++) {
		table.removeChild(mBody[1]);
	}
};

CourseInf.insertTable = function (colNum, rowNum, array, table) {
	var mBody = document.createElement("tbody");
	
	for (var i = 0; i < rowNum; i++) {
		var mTr = document.createElement("tr");
		
		var j = 0;
		for (j = 0; j < colNum; j++) {
			var mCell = document.createElement("td");
			var mText = document.createTextNode(array[j + CourseInf.iCount]);
			
			mCell.appendChild(mText);
			mTr.appendChild(mCell);
		}
		CourseInf.iCount += j;
		mBody.appendChild(mTr);
	}
	table.appendChild(mBody);
};
	
CourseInf.writeTable = function (obj, table) {
	var array = [];
	var className = obj.value;
	
	var iAcc = 0;
	var rowNum = 0;
	var str = "";
	
	for (var i = 0; i < CourseInf.gradeArrays.length; i++) {

		for (var key in CourseInf.gradeArrays[i]) {
			if (CourseInf.gradeArrays[i][key] == className){
				CourseInf.flag = true;
				rowNum++;
			}
			else {	
				if (CourseInf.flag) {
					array[key] = CourseInf.gradeArrays[i][key];
				}
			}

		}
		CourseInf.flag = false;		
		
		if (rowNum != 0) {
			for (var j in array) {
				str = array[j];
				CourseInf.classArrays[iAcc] = str;
				
				iAcc++;
			}
			CourseInf.insertTable(4, 1, CourseInf.classArrays, table);
			
		}
		
		rowNum = 0;		
	}
	
	CourseInf.iCount = 0;
};

CourseInf.readClasses = function (obj) {
	var table = document.getElementById("tb1");
	
	CourseInf.deleteTable(table);
	CourseInf.writeTable(obj, table);
};

CourseInf.loadData = function (array) {
	var data = [];
	var vals = [];
	
	CourseInf.gradeArrays = array;
	
	var obj = document.getElementById("className");

	// json 中键值为"cName"的value值放到数组中
	for (var i = 0; i < array.length; i++) {
		for (var j in array[i]) {
			if (j == "cName")
				data.push(array[i][j]);			
		};
	}

	// 删除重复项
	vals = _uniq(data);
	
	// Traverse Array
	for (var i = 0; i < vals.length; i++) {
		obj.options.add(new Option(vals[i], vals[i]));
	};
	
};


_toObj = function (array) {
	var obj = new Array();
	
	for (var i = 0; i < array.length; i++) {
		obj[array[i]] = true;
	}
	
	return obj;
};

_keys = function (obj) {
	var array = new Array();
	
	for (var i in obj) {
		if (obj.hasOwnProperty(i)) {
			array.push(i);
		};
	}
	
	return array;
};

_uniq = function (array) {
	return _keys(_toObj(array));
};


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