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  • JavaScript写入文件到本地

      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*;.*charsets*=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;
      });
    }
    

      

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  • 原文地址:https://www.cnblogs.com/hapday/p/6292957.html
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