分享html5中localStorage的实例教程

2020-07-28 10:11:34
使用html5的storage来保存数据. 做了个小工具来用一下这个新特性。

需求说明: 有时发现有好的英语表达或者是陌生的单词,总是想记下来,但是过几天之后又不记得了,更别说运用了.

<!DOCTYPE html><head><meta charset="UTF-8"><title>SO EASY!</title><style type="text/css">    html,body {  background-color: #262;        color: #fff;        font-family: helvetica, arial, sans-serif;        margin: 0;        padding: 0;        font-size: 11pt;    }       </style><script lang='text/javascript'>     window.addEventListener("load", eventWindowLoaded, false);     var entries = [];     var curIndex = -1;     function eventWindowLoaded()     {         loadEntries(1);         showNext();         var dayselection = $("dayselection");         dayselection.addEventListener("change", daysSelectionChanged, false);        } function daysSelectionChanged(e)    {        var target = e.target;        loadEntries(target.value);        clearTextarea();        curIndex = -1;        showNext();        log('总共'+entries.length+'个, 当前第'+(curIndex+1)+'个');    }     function loadEntries(days)    {        var now = new Date().getTime();        var arr = [];        for(var i=0; i<localStorage.length; i++)        {            var time = localStorage.key(i);            var daysBetween = (now - time)/24/60/60/1000;            // console.log(daysBetween);            if (daysBetween <= days)            {                var value = JSON.parse(localStorage.getItem(time));                var entry = {time: time, data: value};                arr.push(entry);            }        }        entries = arr;    }    function saveEntry()    {        var data_en = $('en').value;        var data_zh = $('zh').value;        var data = {en: data_en, zh: data_zh};        var time = new Date().getTime();        if (data_en =='' && data_zh == '') // TODO: 正则        {            alert('必须输入中英文表达!');        }        else        {            localStorage.setItem(time, JSON.stringify(data));                           // Update UI            log('保存成功!');            // ReLoad entries            loadEntries($('dayselection').value);            // Recovery current entry            curIndex --;            showNext();        }    }     function deleteEntry()    {        var currentEntry = entries[curIndex];        if (currentEntry)        {            localStorage.removeItem(currentEntry.time);            // Update UI            log('删除成功!');            // Reload entries            loadEntries($('dayselection').value);            // Go to next entry            curIndex --;            showNext();        }    }    function clearStorage()    {        localStorage.clear();        log('数据初始化完成!');    }    function showNext()    {           if (curIndex +1 <= entries.length-1)        {            curIndex ++;            var entry = entries[curIndex];            showTextarea(entry.data);            log('总共'+entries.length+'个, 当前第'+(curIndex+1)+'个');        }    }    function showPrevious()    {        if (curIndex-1 >= 0)        {            curIndex --;            var entry = entries[curIndex];                      showTextarea(entry.data);            log('总共'+entries.length+'个, 当前第'+(curIndex+1)+'个');        }    }    function showTextarea(data)    {        var target_en = $('en');        var target_zh = $('zh');        target_en.value = data.en;        target_zh.value = data.zh;    }    function clearTextarea()    {        $('en').value = '';        $('zh').value = '';    }    function $(id)    {        return document.getElementById(id);    }    function log(msg)    {        var target = document.getElementById('msg');        target.innerHTML = msg;    }    </script></head><body><div style="position: absolute; top: 50px; left: 50px;">    回顾:<select id="dayselection">      <option value="1"> 1天内 </option>      <option value="0.04166666667"> 1小时内 </option>      <option value="3"> 3天内 </option>      <option value="7"> 7天内 </option>      <option value="14"> 14天内 </option>      <option value="30"> 1月内 </option>      <!-- <option value="">  </option> -->    </select>    </tr>    <input type="button" id="prev" value="上一个" onclick="showPrevious();">    <input type="button" id="next" value="下一个" onclick="showNext();">    <hr> 英语表达:<br/>    <textarea id="en" cols="40" rows="6"></textarea>    <hr> 中文解释:<br/>    <textarea id="zh" cols="40" rows="6"></textarea><br/>    <input type="button" id="save" value="保存内容" onclick="saveEntry();">    <input type="button" id="delete" value="删除内容" onclick="deleteEntry();">         <hr> <p id="msg"></p><div></body></html>

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