本文实例讲述了JavaScript实现写入文件到本地的方法。分享给大家供大家参考，具体如下：

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, 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;
 });
}

PS：本站在线工具http://tools.jb51.net上面工具中的很多文件下载功能都是基于FileSaver.js插件实现的，感兴趣的朋友可以查找参考一下。

更多关于JavaScript相关内容感兴趣的读者可查看本站专题：《JavaScript文件与目录操作技巧汇总》、《JavaScript查找算法技巧总结》、《JavaScript数据结构与算法技巧总结》、《JavaScript遍历算法与技巧总结》、《JavaScript错误与调试技巧总结》及《JavaScript数算用法总结》

希望本文所述对大家JavaScript程序设计有所帮助。