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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/
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"]} ];
所谓的动态就是使用删表和写表的操作。
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]); } };
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]; } }
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); };
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>
/* * 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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原文地址:http://blog.csdn.net/xiaobin_hlj80/article/details/45129447