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：
/** * 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：
/* FileSaver.js * A saveAs() FileSaver implementation. * 1.3.2 * 2016-06-16 18:25:19 * * By Eli Grey, * 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 */ 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 =https://www.jb51.net/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; }); }