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）：

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"); 
 }