详解HTML5 LocalStorage 本地存储
1.前言
html5 storage提供了一种方式让网站能够把信息存储到你本地的计算机上，并再以后需要的时候进行获取。这个概念和cookie相似，区别是它是为了更大容量存储设计的。Cookie的大小是受限的，并且每次你请求一个新的页面的时候cookie都会被发送过去。html5的storage是存储在你的计算机上，网站在页面加载完毕后可以通过Javascript来获取这些数据。首先自然是检测浏览器是否支持本地存储。在html5中，本地存储是一个window的属性，包括localStorage和sessionStorage，从名字应该可以很清楚的辨认二者的区别，前者是一直存在本地的，后者只是伴随着session，窗口一旦关闭就没了。二者用法完全相同，这里以localStorage为例。
if(window.localStorage){ alert('支持localStorage');}else{ alert('不支持localStorage');}2.基本用法
存储数据的方法就是直接给window.localStorage添加一个属性，例如：window.localStorage.a 或者 window.localStorage["a"]。它的读取、写、删除操作方法很简单，是以键值对的方式存在的，如下：
localStorage.name = "kobi";//设置name为"kobi"localStorage["name"] = "koko";//设置name为"koko"，覆盖上面的值localStorage.setItem("age","18");//设置age为"18"var a1 = localStorage["name"];//获取name的值var a2 = localStorage.age;//获取age的值var b = localStorage.getItem("name");//获取name的值localStorage.removeItem("c");//清除c的值这里最推荐使用的自然是getItem()和setItem()，清除键值对使用removeItem()。如果希望一次性清除所有的键值对，可以使用clear()。另外，html5还提供了一个key()方法，可以在不知道有哪些键值的时候使用，如下：
var storage = window.localStorage;function showStorage(){ for(var i=0;i<storage.length;i++){ //key(i)获得相应的键，再用getItem()方法获得对应的值 document.write(storage.key(i)+ " : " + storage.getItem(storage.key(i)) + "<br>"); }}3.业务需求
表单实时保存数据，下次打开则提示是否继续编辑。图片等控件不支持，只支持简单的控件。【防止突然断电或浏览器崩溃时，下次打开还可以继续编辑并保存】。这样自然而然就想到了html5的本地存储功能。既然js写的烂，写的差，就当练手了。
其实这些数据的保存很简单，无非就是一些简单的标签数据的保存。先来一个最简单的js版本。
/** * 功能：保存用户修改完form标签内容在LocalStorage中。 * 作者：黄金锋 * 版本：version 2.0 */define(function () { //从localStorage中加载数据 function onload(form) { var fh = form_handler; var p = fh.getParams(form); if (!p.bimId || !p.formId || !p.iid) { return; } var id = 'FORM_' + DCI.LoginUser.UserId + '_' + p.bimId + '_' + p.formId + '_' + p.iid; //alert(id); var formDataDb; var allControl = $(form).find("input:text[name],textarea[name]"); //从本地取 var storage = localStorage.getItem(id); if (storage != null) { var myData = JSON.parse(storage); allControl.each(function (i, e) { var name = $(e).attr("name"); if (myData[name] != null) { $(e).val(myData[name]); $(e).change(); } }); } //绑定change事件 allControl.each(function (i, el) { var name = $(el).attr('name'); if (name) { $(el).on('change', function () { onchange(this); }); } }); //保存修改的数据 function onchange(el) { var storage = localStorage.getItem(id); if (storage == null) { formDataDb = new Object(); var key = $(el).attr("name"); var value = $(el).val(); formDataDb[key] = value; localStorage.setItem(id, JSON.stringify(formDataDb)); } else { var myData = JSON.parse(storage); var key = $(el).attr("name"); var value = $(el).val(); myData[key] = value; localStorage.setItem(id, JSON.stringify(myData)); } } }; //删除localStorage中的数据 function onsave(form) { var fh = form_handler; var p = fh.getParams(form); var id = 'FORM_' + DCI.LoginUser.UserId + '_' + p.bimId + '_' + p.formId + '_' + p.iid; localStorage.removeItem(id); var allGrid = $(form).find(".form-table"); var formId = $(form).data("formid"); allGrid.each(function (index,element) { var formName = $(element).find("input:hidden[data-formid]").attr("name"); var storageKey = "FORM_" + formId + "_" + formName; localStorage.removeItem(storageKey); }); } return { onload: onload, onsave: onsave, }});表单都是自动通过模版生成的，这里附上表单加载需要的form.js.
代码太长，这里就不直接贴出来了，大家自己下载下来看吧 点击这里下载
4.Grid控件的数据保存
Grid控件其实就是一个div，公司的一些页面表单都是动态生成的，表单上面的控件也是动态生成的，所有很多东西都是自己手写的。下面是Grid控件的结构。
<div class="FM000103-SBCLBJ form-table "> <input data-datagrid="true" data-formid="FM000034" name="SBCLBJ" type="hidden" /> <input data-param="init" type="hidden" value="{"ID":"$[ID]","IID":"$(autoid)"}" /> <input data-param="initsame" type="hidden" value="[]" /> <div class="form-table-header"> <div style="width:48px;"> 编辑 </div> <div style="width:50px;"> 序号 </div> <div style="width:60px;"> 是否上传 </div> <div style="width:380px;"> 申报材料内容 </div> <div style="width:80px;"> 备注 </div> </div> <div class="form-table-body"> <table class="table-hover"> <colgroup span="6"> <col width="48" /> <col width="50" data-type="RowNumber" /> <col width="0" data-type="Label" data-index="ID" class="hidden" /> <col width="0" data-type="Label" data-index="IID" class="hidden" /> <col width="60" data-type="CheckBox" data-index="CDZL" /> <col width="380" data-type="TextArea" data-index="ATDESC" /> <col width="80" data-type="TextArea" data-index="BZ" /> </colgroup> <tbody> <tr> <td class="form-table-edit"><span class="glyphicon glyphicon-edit" aria-hidden="true"></span></td> <td>1</td> <td class="hidden">BM00001141</td> <td class="hidden">4643</td> <td><input type="checkbox" value="1" checked="checked" /></td> <td>11111</td> <td>2222</td> </tr> <tr> <td class="form-table-edit"><span class="glyphicon glyphicon-edit" aria-hidden="true"></span></td> <td>2</td> <td class="hidden">BM00001141</td> <td class="hidden">4644</td> <td><input type="checkbox" value="0" /></td> <td>87789789789798789</td> <td>333</td> </tr> </tbody> </table> </div> <div class="form-table-footer"> <button type="button" class="btn add-row">新增</button> <button type="button" class="btn del-row">删除</button> </div> </div>下面是完成Grid数据保存的js.
/** * 功能：保存用户修改完form标签内容在LocalStorage中。 * 作者：黄金锋 (549387177@qq.com) * 日期：2015-11-1 11:14:01 * 修改：2015-11-19 16:09:00 * 版本：version 3.0 */define(function () { //从localStorage中加载数据 function onload(form) { var fh = form_handler; var p = fh.getParams(form); if (!p.bimId || !p.formId || !p.iid) { return; } var id = 'FORM_' + DCI.LoginUser.UserId + '_' + p.bimId + '_' + p.formId + '_' + p.iid; var formDataDb; var allControl = $(form).find("input:text[name],textarea[name]"); //从本地取 var storage = localStorage.getItem(id); if (storage != null) { if (confirm("是否加载缓存数据")) { var myData = JSON.parse(storage); allControl.each(function (i, e) { var name = $(e).attr("name"); if (myData[name] != null) { $(e).val(myData[name]); $(e).change(); } }); } } var allGrid = $(form).find(".form-table"); var formId = $(form).data("formid"); var formStorage= localStorage.getItem("FORM_" + formId + "_isGridData"); if (formStorage=="1") { if (confirm("是否加载Grid缓存数据")) { //给Grid控件赋值 allGrid.each(function (index, element) { var formName = $(element).find("input:hidden[data-formid]").attr("name"); var ipt = $(element).find("input[name]"); var table = $(element).find("input:hidden[data-formid]").siblings(".form-table-body").find(".table-hover"); var storageKey = "FORM_" + formId + "_" + formName; var data = localStorage.getItem(storageKey); var myData = JSON.parse(data); if (myData != null) { alert(data); var InsertTotal = myData["Total"]["InsertTotal"]; var DelTotal = myData["Total"]["DelTotal"]; var UpdateTotal = myData["Total"]["UpdateTotal"]; var trIIDIndex = myData["trIIDIndex"]["IID"]; if (InsertTotal > 0) { for (var i = 0; i < InsertTotal; i++) { var tr = $('<tr></tr>'); var row_data = myData["Insert"][i]; table.find('colgroup col').each(function (idx, el) { var td = $('<td></td>'); if (idx == 0) { td.append('<span class="glyphicon glyphicon-edit" aria-hidden="true"></span>'); td.addClass('form-table-edit'); } else { var index = $(el).data('index'); var type = $(el).data('type') if (type == "RowNumber") { var val = row_data["RowNumber"]; td.html(val); } if (type == "CheckBox") { var val = row_data[index]; td.append('<input type="checkbox" value="' + val + '" ' + (val == '1' ? 'checked="checked"' : '') + ' />'); } if (index && type != "CheckBox") { td.html(row_data[index]); } } if ($(el).attr('width') == '0') td.addClass('hidden'); td.appendTo(tr); }); //table.find("tbody").append(tr); table.append(tr); tr.data("insert", true); ipt.change(); } } if (UpdateTotal > 0) { for (var i = 0; i < UpdateTotal; i++) { var row_data = myData["Update"][i]; var trIID = row_data["trIID"]; var trIndex; table.find("tr").each(function (idx, ele) { var iid = $(ele).find("td").eq(trIIDIndex).html(); if (iid == trIID) { trIndex = idx; } }); var cells = table.find("tr").eq(trIndex); table.find('colgroup col').each(function (idx, el) { var index = $(el).data('index'); if (index) { var td = cells.find("td").eq(idx); var type = $(el).data('type'); var test =new Object(); var text = row_data[index]; if (type == 'CheckBox') { var ck = td.find('input[type="checkbox"]'); if (text == '1') ck.prop('checked', true); else ck.prop('checked', false); } else { td.text(text); } } }); cells.data("update", true); ipt.change(); } } if (DelTotal > 0) { for (var i = 0; i < DelTotal; i++) { var row_data = myData["Del"][i]; var trIID = row_data["trIID"]; table.find("tr").each(function (idx,ele) { var iid = $(ele).find("td").eq(trIIDIndex).html(); if ( iid== trIID) { $(this).css("display", "none"); $(this).data("delete", true); ipt.change(); } }); } } } }); } } //绑定change事件 allControl.each(function (i, el) { var name = $(el).attr('name'); if (name) { $(el).on('change', function () { onchange(this); }); } }); //保存修改的数据 function onchange(el) { var storage = localStorage.getItem(id); if (storage == null) { formDataDb = new Object(); var key = $(el).attr("name"); var value = $(el).val(); formDataDb[key] = value; localStorage.setItem(id, JSON.stringify(formDataDb)); } else { var myData = JSON.parse(storage); var key = $(el).attr("name"); var value = $(el).val(); myData[key] = value; localStorage.setItem(id, JSON.stringify(myData)); } } }; //删除localStorage中的数据 function onsave(form) { var fh = form_handler; var p = fh.getParams(form); var id = 'FORM_' + DCI.LoginUser.UserId + '_' + p.bimId + '_' + p.formId + '_' + p.iid; localStorage.removeItem(id); var allGrid = $(form).find(".form-table"); var formId = $(form).data("formid"); allGrid.each(function (index,element) { var formName = $(element).find("input:hidden[data-formid]").attr("name"); var storageKey = "FORM_" + formId + "_" + formName; localStorage.removeItem(storageKey); }); localStorage.setItem("FORM_" + formId + "_isGridData", null); } function ongridadd(form, table, data, tr) { var inputflag = table.closest("div .form-table").find("input:hidden[data-formid]") var storageKey; var formId = $(form).data("formid");; localStorage.setItem("FORM_" + formId + "_isGridData", "1"); var RowNumber = table.find(".active").children().eq(1).html(); var trIIDIndex; var trIID; table.find("col").each(function (idx, ele) { if ($(ele).data("index") == "IID") { trIID = table.find(".active").children().eq(idx).html(); trIIDIndex = idx; } }); var InsertObj = { trIID: trIID, RowNumber: RowNumber }; var columnArr = table.children().find("[data-index]"); if (columnArr) { columnArr.each(function (index, element) { var flag = $(element).data("index"); InsertObj[flag] = data[flag]; }); } if (inputflag && trIID) { storageKey = "FORM_" + formId + "_" + inputflag.attr("name"); //var mydata = "{'Insert':[{'trIID':'1','ID':'test','IID':'测试'},{'trIID':'2','ID':'test2','IID':'测试2'}],'Update':[{'trIID':'3','ID':'test3','IID':'测试3'},{'trIID':'4','ID':'test4','IID':'测试4'}],'Del':[{'trIID':'1'},{'trIID':'2'}]}"; var getLocalStorage = localStorage.getItem(storageKey); if (getLocalStorage) { var dataObj = JSON.parse(getLocalStorage); var InsertTotal = dataObj["Total"]["InsertTotal"]; dataObj["Insert"][InsertTotal] = InsertObj; dataObj["Total"]["InsertTotal"] = InsertTotal + 1; localStorage.setItem(storageKey, JSON.stringify(dataObj)); } else { var mydata = { Total: { InsertTotal: 1, UpdateTotal: 0, DelTotal: 0 }, Insert: [InsertObj], Update: [], Del: [], Notes: { storageKey: storageKey }, trIIDIndex: { IID: trIIDIndex } }; localStorage.setItem(storageKey, JSON.stringify(mydata)); } } } function ongridedit(form, table, data, tr) { var inputflag = table.closest("div .form-table").find("input:hidden[data-formid]") var formId = $(form).data("formid"); var storageKey = "FORM_" + formId + "_" + inputflag.attr("name"); localStorage.setItem("FORM_" + formId + "_isGridData", "1"); var mySourceData = {}; var trIIDIndex; table.find("col").each(function (idx, ele) { var index = $(ele).data("index"); var type = $(ele).data("type"); if (index) { if (type == "CheckBox") { var val = table.find(".active").children().eq(idx).html(); var value =$(val).val(); mySourceData[index] = value; } else { if (index == "IID") { trIIDIndex = idx; } mySourceData[index] = table.find(".active").children().eq(idx).html(); } } }); var trIID = mySourceData["IID"]; var UpdateObj = { trIID: trIID }; $.extend(UpdateObj, mySourceData); var getLocalStorage = localStorage.getItem(storageKey); if (getLocalStorage) { var dataObj = JSON.parse(getLocalStorage); var InsertTotal = dataObj["Total"]["InsertTotal"]; var UpdateTotal = dataObj["Total"]["UpdateTotal"]; if (InsertTotal > 0)//新增后在编辑 { for (var i = 0; i < InsertTotal; i++) { var row_data = dataObj["Insert"][i]; if (row_data["trIID"] == trIID) { $.extend(dataObj["Insert"][i], UpdateObj); } } } if (UpdateTotal > 0)//编辑之后在编辑 { for (var i = 0; i < UpdateTotal; i++) { var row_data = dataObj["Update"][i]; if (row_data["trIID"] == trIID) { $.extend(dataObj["Update"][i], UpdateObj); } } } var UpdateTotal = dataObj["Total"]["UpdateTotal"]; dataObj["Update"][UpdateTotal] = UpdateObj; dataObj["Total"]["UpdateTotal"] = UpdateTotal + 1; localStorage.setItem(storageKey, JSON.stringify(dataObj)); } else { var mydata = { Total: { InsertTotal: 0, UpdateTotal: 1, DelTotal: 0 }, Insert: [], Update: [UpdateObj], Del: [], Notes: { storageKey: storageKey }, trIIDIndex: { IID: trIIDIndex } }; localStorage.setItem(storageKey, JSON.stringify(mydata)); } var testdata = localStorage.getItem(storageKey); var myData = JSON.parse(testdata); if (testdata != null) { alert(testdata); //alert(mydata); //alert(myData["Total"]["InsertTotal"]); //alert(myData["Insert"][0]["ID"]); } } function ongriddel(form, table, tr) { var inputflag = table.closest("div .form-table").find("input:hidden[data-formid]") var formId = $(form).data("formid"); var storageKey = "FORM_" + formId + "_" + inputflag.attr("name");; localStorage.setItem("FORM_" + formId + "_isGridData", "1"); var trIIDIndex; var trIID; table.find("col").each(function (idx, ele) { if ($(ele).data("index") == "IID") { trIIDIndex = idx; trIID = tr.find("td").eq(idx).html(); } }); var DelObj = { trIID: trIID }; var getLocalStorage = localStorage.getItem(storageKey); if (getLocalStorage) { var dataObj = JSON.parse(getLocalStorage); var isInsertData = false; var isUpdateDel = false; var InsertTotal = dataObj["Total"]["InsertTotal"]; var DelTotal = dataObj["Total"]["DelTotal"]; var UpdateTotal = dataObj["Total"]["UpdateTotal"]; if (InsertTotal > 0) { for (var i = 0; i < InsertTotal; i++) { var row_data = dataObj["Insert"][i]; if (row_data["trIID"] == trIID) { isInsertData = true; dataObj["Insert"][i] = null; } } } if (UpdateTotal>0) { for (var i = 0; i < UpdateTotal; i++) { var row_data = dataObj["Update"][i]; if (row_data["trIID"] == trIID) { isUpdateDel = true; dataObj["Update"][i] = null; } } } if (isInsertData) { var tempArr = []; for (var i = 0; i < InsertTotal; i++) { if (dataObj["Insert"][i] != null) { tempArr[i]=dataObj["Insert"][i]; } } dataObj["Insert"] = tempArr; dataObj["Total"]["InsertTotal"] = InsertTotal - 1; } else { if (isUpdateDel) { var tempArr = []; for (var i = 0; i < InsertTotal; i++) { if (dataObj["Update"][i] != null) { tempArr[i] = dataObj["Update"][i]; } } dataObj["Update"] = tempArr; dataObj["Total"]["UpdateTotal"] = UpdateTotal - 1; } dataObj["Del"][DelTotal] = DelObj; dataObj["Total"]["DelTotal"] = DelTotal + 1; } localStorage.setItem(storageKey, JSON.stringify(dataObj)); if (dataObj["Total"]["InsertTotal"] == 0 && dataObj["Total"]["UpdateTotal"] == 0 && dataObj["Total"]["DelTotal"] == 0) { localStorage.setItem("FORM_" + formId + "_isGridData", null); } } else { var mydata = { Total: { InsertTotal: 0, UpdateTotal: 0, DelTotal: 1 }, Insert: [], Update: [], Del: [DelObj], Notes: { storageKey: storageKey }, trIIDIndex: { IID: trIIDIndex } }; localStorage.setItem(storageKey, JSON.stringify(mydata)); } } return { onload: onload, onsave: onsave, ongridadd: ongridadd, ongridedit: ongridedit, ongriddel: ongriddel }});以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
最后更新于 2021-10-23 07:48:12 并被添加「」标签，已有 位童鞋阅读过。
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