JavaScript实现写入文件到本地的方法【基于FileSaver.js插件】

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。

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希望本文所述对大家javascript程序设计有所帮助。