JavaScript写入文件到本地

　　工作中有时需要通过 JavaScript 保存文件到本地，我们都知道 JavaScript 基于安全的考虑，是不允许直接操作本地文件的。
IE 可以通过 VB 插件的方式进行，而 Chrome 和 firefox 都不支持 JavaScript 向本地写入文件，所以 VB 插件的方式存在兼容性问题。
那有没有适合的方法呢？答案是肯定的，我们可以通过 FileSaver.js 这个小插件实现我们的需求。下面看一段具体的代码吧：

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/**  * 下载文件  */ var downloadTextFile = function(mobileCode) {     if(isEmpty(mobileCode)) {         mobileCode = '';     }           var file = new File([mobileCode], "手机号.txt", { type: "text/plain;charset=utf-8" });     saveAs(file); }

　　这个示例是向本地存储一个名字叫“手机号.txt”的文本文件，采用的字符编码格式为“UTF-8”，这样就避免的中文乱码的问题。聪明的你也赶快试试吧！

 

 

附 FileSaver.js 文件的完整源码：

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/* FileSaver.js  * A saveAs() FileSaver implementation.  * 1.3.2  * 2016-06-16 18:25:19  *  * By Eli Grey, http://eligrey.com  * License: MIT  *   See https://github.com/eligrey/FileSaver.js/blob/master/LICENSE.md  */   /*global self */ /*jslint bitwise: true, indent: 4, laxbreak: true, laxcomma: true, smarttabs: true, plusplus: true */   /*! @source http://purl.eligrey.com/github/FileSaver.js/blob/master/FileSaver.js */   var saveAs = saveAs || (function(view) {     "use strict";     // IE <10 is explicitly unsupported     if (typeof view === "undefined" || typeof navigator !== "undefined" && /MSIE [1-9]\./.test(navigator.userAgent)) {         return;     }     var           doc = view.document           // only get URL when necessary in case Blob.js hasn't overridden it yet         , get_URL = function() {             return view.URL || view.webkitURL || view;         }         , save_link = doc.createElementNS("http://www.w3.org/1999/xhtml", "a")         , can_use_save_link = "download" in save_link         , click = function(node) {             var event = new MouseEvent("click");             node.dispatchEvent(event);         }         , is_safari = /constructor/i.test(view.HTMLElement) || view.safari         , is_chrome_ios =/CriOS\/[\d]+/.test(navigator.userAgent)         , throw_outside = function(ex) {             (view.setImmediate || view.setTimeout)(function() {                 throw ex;             }, 0);         }         , force_saveable_type = "application/octet-stream"         // the Blob API is fundamentally broken as there is no "downloadfinished" event to subscribe to         , arbitrary_revoke_timeout = 1000 * 40 // in ms         , revoke = function(file) {             var revoker = function() {                 if (typeof file === "string") { // file is an object URL                     get_URL().revokeObjectURL(file);                 } else { // file is a File                     file.remove();                 }             };             setTimeout(revoker, arbitrary_revoke_timeout);         }         , dispatch = function(filesaver, event_types, event) {             event_types = [].concat(event_types);             var i = event_types.length;             while (i--) {                 var listener = filesaver["on" + event_types[i]];                 if (typeof listener === "function") {                     try {                         listener.call(filesaver, event || filesaver);                     } catch (ex) {                         throw_outside(ex);                     }                 }             }         }         , auto_bom = function(blob) {             // prepend BOM for UTF-8 XML and text/* types (including HTML)             // note: your browser will automatically convert UTF-16 U+FEFF to EF BB BF             if (/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(blob.type)) {                 return new Blob([String.fromCharCode(0xFEFF), blob], {type: blob.type});             }             return blob;         }         , FileSaver = function(blob, name, no_auto_bom) {             if (!no_auto_bom) {                 blob = auto_bom(blob);             }             // First try a.download, then web filesystem, then object URLs             var                   filesaver = this                 , type = blob.type                 , force = type === force_saveable_type                 , object_url                 , dispatch_all = function() {                     dispatch(filesaver, "writestart progress write writeend".split(" "));                 }                 // on any filesys errors revert to saving with object URLs                 , fs_error = function() {                     if ((is_chrome_ios || (force && is_safari)) && view.FileReader) {                         // Safari doesn't allow downloading of blob urls                         var reader = new FileReader();                         reader.onloadend = function() {                             var url = is_chrome_ios ? reader.result : reader.result.replace(/^data:[^;]*;/, 'data:attachment/file;');                             var popup = view.open(url, '_blank');                             if(!popup) view.location.href = url;                             url=undefined; // release reference before dispatching                             filesaver.readyState = filesaver.DONE;                             dispatch_all();                         };                         reader.readAsDataURL(blob);                         filesaver.readyState = filesaver.INIT;                         return;                     }                     // don't create more object URLs than needed                     if (!object_url) {                         object_url = get_URL().createObjectURL(blob);                     }                     if (force) {                         view.location.href = object_url;                     } else {                         var opened = view.open(object_url, "_blank");                         if (!opened) {                             // Apple does not allow window.open, see https://developer.apple.com/library/safari/documentation/Tools/Conceptual/SafariExtensionGuide/WorkingwithWindowsandTabs/WorkingwithWindowsandTabs.html                             view.location.href = object_url;                         }                     }                     filesaver.readyState = filesaver.DONE;                     dispatch_all();                     revoke(object_url);                 }             ;             filesaver.readyState = filesaver.INIT;               if (can_use_save_link) {                 object_url = get_URL().createObjectURL(blob);                 setTimeout(function() {                     save_link.href = object_url;                     save_link.download = name;                     click(save_link);                     dispatch_all();                     revoke(object_url);                     filesaver.readyState = filesaver.DONE;                 });                 return;             }               fs_error();         }         , FS_proto = FileSaver.prototype         , saveAs = function(blob, name, no_auto_bom) {             return new FileSaver(blob, name || blob.name || "download", no_auto_bom);         }     ;     // IE 10+ (native saveAs)     if (typeof navigator !== "undefined" && navigator.msSaveOrOpenBlob) {         return function(blob, name, no_auto_bom) {             name = name || blob.name || "download";               if (!no_auto_bom) {                 blob = auto_bom(blob);             }             return navigator.msSaveOrOpenBlob(blob, name);         };     }       FS_proto.abort = function(){};     FS_proto.readyState = FS_proto.INIT = 0;     FS_proto.WRITING = 1;     FS_proto.DONE = 2;       FS_proto.error =     FS_proto.onwritestart =     FS_proto.onprogress =     FS_proto.onwrite =     FS_proto.onabort =     FS_proto.onerror =     FS_proto.onwriteend =         null;       return saveAs; }(        typeof self !== "undefined" && self     || typeof window !== "undefined" && window     || this.content )); // `self` is undefined in Firefox for Android content script context // while `this` is nsIContentFrameMessageManager // with an attribute `content` that corresponds to the window   if (typeof module !== "undefined" && module.exports) {   module.exports.saveAs = saveAs; } else if ((typeof define !== "undefined" && define !== null) && (define.amd !== null)) {   define("FileSaver.js", function() {     return saveAs;   }); }