js基于FileSaver.js 浏览器导出Excel文件的示例

本文介绍了js基于FileSaver.js 浏览器导出Excel文件，分享给大家，也给自己做个笔记

限制一：不同浏览器对 blob 对象有不同的限制

具体看看下面这个表格（出自FileSaver.js）：

Browser	Constructs as	Filenames	Max Blob Size	Dependencies
Firefox 20+	Blob	Yes	800 MiB	None
Firefox < 20	data: URI	No	n/a	Blob.js
Chrome	Blob	Yes	500 MiB	None
Chrome for Android	Blob	Yes	500 MiB	None
Edge	Blob	Yes	?	None
IE 10+	Blob	Yes	600 MiB	None
Opera 15+	Blob	Yes	500 MiB	None
Opera < 15	data: URI	No	n/a	Blob.js
Safari 6.1+*	Blob	No	?	None
Safari < 6	data: URI	No	n/a	Blob.js

限制二：构建完 blob 对象后才会转换成文件

这一点限制对小文件(几十kb)可能没什么影响，但对稍微大一点的文件影响就很大了。试想，用户要下载一个 100mb 的文件，如果他点击了下载按钮之后没看到下载提示的话，他肯定会继续按，等他按了几次之后还没看到下载提示时，他就会抱怨我们的网站，然后离开了。

然而事实上下载的的确确发生了，只是要等到下载完文件之后才能构建 blob 对象，再转化成文件。而且，用户再触发多几次下载就会造成一些资源上的浪费。

因此，如果是要下载大文件的话，还是推荐直接创建一个 <a> 标签拉~
写 html 也好，写 JavaScript 动态创建也好，用自己喜欢的方式去创建就好了。

FileSaver.js 

/* FileSaver.js
 * A saveAs() FileSaver implementation.
 * 1.3.2
 * 2016-06-16 18:25:19
 *
 * 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;
 });
}

调用方法

 function expToExcel(){
      var content = $("#report").html();
      var blob = new Blob(["Hello, world!"], { type: "text/plain;charset=utf-8" });
      saveAs(blob, "hello world.txt");      
    }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持呐喊教程。

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