详解HTML5 LocalStorage 本地存储
(编辑：jimmy 日期: 2024/11/28 浏览：3 次 )
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。
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