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:
rush:js;">
/**
* 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:
rush:js;">
/* 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,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,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。
更多关于JavaScript相关内容感兴趣的读者可查看本站专题:《》、《》、《》、《》、《》及《用法总结》
希望本文所述对大家JavaScript程序设计有所帮助。
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