下载localstorage的数据并保存为文件 Aug 13, 2016 javascript 下载localstorage的数据并保存为文件 写插件,或者用到localstorage的时候,强依赖localstorage的应用,就很怕localstorage的数据被清空,或者数据无法共享啊什么的。。 有痛点,怎么解决? 导出localstorage的数据,备份啊,共享啊什么的,都能解决了。。。于是有了下面的一段代码 主要原理是使用data属性,把需要导出的数据base64,然后就好了,没了,就这么简单。。。(在chrome上测试通过) /* * $Id: base64.js,v 2.15 2014/04/05 12:58:57 dankogai Exp dankogai $ * * Licensed under the BSD 3-Clause License. * http://opensource.org/licenses/BSD-3-Clause * * References: * http://en.wikipedia.org/wiki/Base64 */ (function(global) { 'use strict'; // existing version for noConflict() var _Base64 = global.Base64; var version = "2.1.9"; // if node.js, we use Buffer var buffer; if (typeof module !== 'undefined' && module.exports) { try { buffer = require('buffer').Buffer; } catch (err) {} } // constants var b64chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'; var b64tab = function(bin) { var t = {}; for (var i = 0, l = bin.length; i < l; i++) t[bin.charAt(i)] = i; return t; }(b64chars); var fromCharCode = String.fromCharCode; // encoder stuff var cb_utob = function(c) { if (c.length < 2) { var cc = c.charCodeAt(0); return cc < 0x80 ? c : cc < 0x800 ? (fromCharCode(0xc0 | (cc >>> 6)) + fromCharCode(0x80 | (cc & 0x3f))) : (fromCharCode(0xe0 | ((cc >>> 12) & 0x0f)) + fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) + fromCharCode(0x80 | ( cc & 0x3f))); } else { var cc = 0x10000 + (c.charCodeAt(0) - 0xD800) * 0x400 + (c.charCodeAt(1) - 0xDC00); return (fromCharCode(0xf0 | ((cc >>> 18) & 0x07)) + fromCharCode(0x80 | ((cc >>> 12) & 0x3f)) + fromCharCode(0x80 | ((cc >>> 6) & 0x3f)) + fromCharCode(0x80 | ( cc & 0x3f))); } }; var re_utob = /[\uD800-\uDBFF][\uDC00-\uDFFFF]|[^\x00-\x7F]/g; var utob = function(u) { return u.replace(re_utob, cb_utob); }; var cb_encode = function(ccc) { var padlen = [0, 2, 1][ccc.length % 3], ord = ccc.charCodeAt(0) << 16 | ((ccc.length > 1 ? ccc.charCodeAt(1) : 0) << 8) | ((ccc.length > 2 ? ccc.charCodeAt(2) : 0)), chars = [ b64chars.charAt( ord >>> 18), b64chars.charAt((ord >>> 12) & 63), padlen >= 2 ? '=' : b64chars.charAt((ord >>> 6) & 63), padlen >= 1 ? '=' : b64chars.charAt(ord & 63) ]; return chars.join(''); }; var btoa = global.btoa ? function(b) { return global.btoa(b); } : function(b) { return b.replace(/[\s\S]{1,3}/g, cb_encode); }; var _encode = buffer ? function (u) { return (u.constructor === buffer.constructor ? u : new buffer(u)) .toString('base64') } : function (u) { return btoa(utob(u)) } ; var encode = function(u, urisafe) { return !urisafe ? _encode(String(u)) : _encode(String(u)).replace(/[+\/]/g, function(m0) { return m0 == '+' ? '-' : '_'; }).replace(/=/g, ''); }; var encodeURI = function(u) { return encode(u, true) }; // decoder stuff var re_btou = new RegExp([ '[\xC0-\xDF][\x80-\xBF]', '[\xE0-\xEF][\x80-\xBF]{2}', '[\xF0-\xF7][\x80-\xBF]{3}' ].join('|'), 'g'); var cb_btou = function(cccc) { switch(cccc.length) { case 4: var cp = ((0x07 & cccc.charCodeAt(0)) << 18) | ((0x3f & cccc.charCodeAt(1)) << 12) | ((0x3f & cccc.charCodeAt(2)) << 6) | (0x3f & cccc.charCodeAt(3)), offset = cp - 0x10000; return (fromCharCode((offset >>> 10) + 0xD800) + fromCharCode((offset & 0x3FF) + 0xDC00)); case 3: return fromCharCode( ((0x0f & cccc.charCodeAt(0)) << 12) | ((0x3f & cccc.charCodeAt(1)) << 6) | (0x3f & cccc.charCodeAt(2)) ); default: return fromCharCode( ((0x1f & cccc.charCodeAt(0)) << 6) | (0x3f & cccc.charCodeAt(1)) ); } }; var btou = function(b) { return b.replace(re_btou, cb_btou); }; var cb_decode = function(cccc) { var len = cccc.length, padlen = len % 4, n = (len > 0 ? b64tab[cccc.charAt(0)] << 18 : 0) | (len > 1 ? b64tab[cccc.charAt(1)] << 12 : 0) | (len > 2 ? b64tab[cccc.charAt(2)] << 6 : 0) | (len > 3 ? b64tab[cccc.charAt(3)] : 0), chars = [ fromCharCode( n >>> 16), fromCharCode((n >>> 8) & 0xff), fromCharCode( n & 0xff) ]; chars.length -= [0, 0, 2, 1][padlen]; return chars.join(''); }; var atob = global.atob ? function(a) { return global.atob(a); } : function(a){ return a.replace(/[\s\S]{1,4}/g, cb_decode); }; var _decode = buffer ? function(a) { return (a.constructor === buffer.constructor ? a : new buffer(a, 'base64')).toString(); } : function(a) { return btou(atob(a)) }; var decode = function(a){ return _decode( String(a).replace(/[-_]/g, function(m0) { return m0 == '-' ? '+' : '/' }) .replace(/[^A-Za-z0-9\+\/]/g, '') ); }; var noConflict = function() { var Base64 = global.Base64; global.Base64 = _Base64; return Base64; }; // export Base64 global.Base64 = { VERSION: version, atob: atob, btoa: btoa, fromBase64: decode, toBase64: encode, utob: utob, encode: encode, encodeURI: encodeURI, btou: btou, decode: decode, noConflict: noConflict }; // if ES5 is available, make Base64.extendString() available if (typeof Object.defineProperty === 'function') { var noEnum = function(v){ return {value:v,enumerable:false,writable:true,configurable:true}; }; global.Base64.extendString = function () { Object.defineProperty( String.prototype, 'fromBase64', noEnum(function () { return decode(this) })); Object.defineProperty( String.prototype, 'toBase64', noEnum(function (urisafe) { return encode(this, urisafe) })); Object.defineProperty( String.prototype, 'toBase64URI', noEnum(function () { return encode(this, true) })); }; } // that's it! if (global['Meteor']) { Base64 = global.Base64; // for normal export in Meteor.js } })(this); !(function(){ var link = document.createElement('a'); link.href = '#'; link.download = 'data.json'; link.href = 'data:application/json;base64,' + Base64.encode(localStorage.getItem('data')); document.body.appendChild(link); link.click(); })(); Edit this page