html学习笔记（15）

来源：互联网发布：rf mems 知乎编辑：程序博客网时间：2024/06/03 18:24

indexedDB数据库索引：

<!DOCTYPE html><html><head lang="en">    <meta charset="UTF-8">    <title></title>    <script>        var myDB = {            name:"helloindexDB",            version:1,            db:null        }        function opendb(name, version){            var version = version || 1;            var request = window.indexedDB.open(name, version);            request.onsuccess = function(e){                myDB.db  = e.target.result;                alert("数据库连接成功");            }            request.onerror = function(){                alert("连接数据库失败")            }            request.onupgradeneeded = function(e){                var db = e.target.result;                if(!db.objectStoreNames.contains("students")){                    var store = db.createObjectStore("students", {keyPath:"id"});                    //createIndex(索引名称，索引字段， 是否唯一)                    store.createIndex("nameIndex", "name", {unique:true});                    store.createIndex("ageIndex", "age", {unique:false});                }            }        }        var students =[{            id:101,            name:"sss",            age:10        },{            id:102,            name:"ss",            age:12        },{            id:103,            name:"ssss",            age:13        }        ];        function addData(db, storeName){            var transaction = db.transaction(storeName, "readwrite");            var store = transaction.objectStore(storeName);            for(var i=0; i<students.length; i++){                store.add(students[i]);            }        }        opendb(myDB.name, myDB.version);        setTimeout(function(){            addData(myDB.db, "students");        },1000);        //name        function getDataByIndexName(db, storeName){            var transaction = db.transaction(storeName);            var store = transaction.objectStore(storeName);            var index = store.index("nameIndex");            index.get("ss").onsuccess = function(e){                var student = e.target.result;                console.log(student.name + "----" + student.age + "----" + student.id);            }        }        setTimeout(function(){            getDataByIndexName(myDB.db, "students");        },1000);        //age        function getDataByIndexName(db, storeName){            var transaction = db.transaction(storeName);            var store = transaction.objectStore(storeName);            var index = store.index("ageIndex");            index.get(13).onsuccess = function(e){                var student = e.target.result;                console.log(student.name + "----" + student.age + "----" + student.id);            }        }        setTimeout(function(){            getDataByIndexName(myDB.db, "students");        },1000);    </script></head><body><!--索引：迅速定位数据，keypass方式索引： createindex(索引名称， 索引属性字段名， 索引属性值是否唯一)--></body></html>

创建游标

//创建游标：        function fetchStoreByCursor(db, storeName){            var transaction = db.transaction(storeName);            var store = transaction.objectStore(storeName);            var request = store.openCursor();            request.onsuccess = function(e){                var cursor = e.target.result;                if(cursor){                    console.log(cursor.key);                    var currentStudent = cursor.value;                    console.log(currentStudent.name);                    //游标下移                    cursor.continue();                }            }        }        setTimeout(function(){            fetchStoreByCursor(myDB.db, "students");        },1000)

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