动态生成表格 - javascript

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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 Arrayfor (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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