nodejs脚本-将网络图片转成base64码方便写md插图

#!/usr/bin/node

'use strict';

const HELP = `
/***********************README***************************
 * 适用环境：Ubuntu18.04
 * 
 * 脚本所需模块：
 *  Node原生模块：fs、child_process
 *  第三方模块：http、https、clipboard（可选）
 * 
 * 其中fs用于生成临时文档文件以免字符过多时可查看文档
 * 其中child_process用于执行linux命令，搭配clipboard模块适用
 * 其中clipboard模块用于粘贴文本到剪贴板中
 * 安装:sudo npm install -g clipboard-cli
 * 
 * 支持网络图片格式：
 * 	jpg,png,webp,svg
 * 
 * 支持本地图片格式：
 * 	jpg,png,webp,svg
 * 
 * 脚本支持参数：
 *  -v, --version 	查看版本
 *  -t, --test		拉取网络示例图片测试
 *  -h, --help		查看帮助文档
 * 
 * 临时文件存放格式：
 * /tmp/img2base64-[DateTime]
 * 
 * 报错处理：
 * throw errnoException(err, 'spawn');
 * Error: spawn E2BIG
 * 
 ********************************************************/
 `
const VERSION = '1.0-alpha';
const AUTHOR = 'Chanj Wang';
const DATE = '2020-05-13 AM'
const PRINTINFO = `Img2Base64 version is: ${VERSION} by ${AUTHOR} at ${DATE}`;

var fs = require('fs');
var http = require('http');
var https = require('https');
var exec = require('child_process').exec;

var httpModule = {http: http, https: https};
var argv = global.process.argv;

const READFROMWEB = 0;
const READFROMLOCAL = 1;
const TMPFILE = "/tmp/img2base64-"
const FILENAME = TMPFILE + new Date().toJSON().replace(/\:|\./g, "-");

var readmode;
var imgUrl = "";
var imgHttpType = "";
var imgType = "";

if (/^-+\w+$/.test(argv[2])) {
	switch (argv[2].match(/\w+/)[0]) {
		case 'v':
		case 'version':
			console.log('\x1B[32m%s\x1B[39m', PRINTINFO);
			return;
		case 'h':
		case 'help':
			console.log('\x1B[33m%s\x1B[0m', HELP);
			return;
		case 't':
		case 'test':
			imgUrl = 'http://www.baidu.com/img/baidu_jgylogo3.gif';
	}
} else {
	imgUrl = argv[2];
}

if (/^http(s)?:\/\//.test(imgUrl)) {
	readmode = READFROMWEB;
	imgHttpType = imgUrl.match(/^(\w+)\:/)[1];
} else {
	readmode = READFROMLOCAL;
}

imgType = getImgType(imgUrl);

if (readmode == 0) {
	getBase64FromWeb(imgHttpType, imgUrl, imgType);
} else {
	getBase64FromLocal(imgUrl, imgType);
}


function execCommand(Command) {
	exec(Command, function(err, stdout, stderr) {
		if (err || stderr) {
			console.error("\n复制到剪贴板失败！请直接查看上面路径文档进行复制");
			return;
		}
		
		console.log("\n复制到剪贴板成功！");
	})
}

function converseImgBase64WithPrefix(ImgType, Base64String) {
	var imgBase64ForMarkdown = "data:image/" + ImgType + ";base64," + Base64String;
	
	return imgBase64ForMarkdown;
}

function getImgType(Url) {
	var type = (Url.match(/\.(\w+)$/) && Url.match(/\.(\w+)$/)[1]) || "jpg";
	
	if (type === "svg") {
		type += "+xml";
	}

	return type;
}

function writeStream(Data, Filepath) {
	return new Promise((resolve, reject) => {
		var writerStream = fs.createWriteStream(Filepath);
	
		writerStream.write(Data, 'UTF8');
		
		writerStream.end();
		
		writerStream.on('finish', function() {
			console.log("临时文件写入完成,文件路径： ", Filepath);
			resolve(1);
		});
		
		writerStream.on('error', function(err){
			console.log(err.stack);
			reject(0);
		});
	})
}

function getBase64FromWeb(HttpType, Url, ImgType) {
	httpModule[HttpType].get(Url, function(res){
		var chunks = [];
		var size = 0;
	
		res.on('data', function(chunk){
			chunks.push(chunk);
			size += chunk.length;
		})
	
		res.on('end', function(err){
			var imgData = Buffer.concat(chunks, size);

			var imgBase64 = imgData.toString("base64");
	
			var imgBase64ForMarkdown = converseImgBase64WithPrefix(ImgType, imgBase64);
	
			writeStream(imgBase64ForMarkdown, FILENAME)
				.then(() => {
					var cmd = 'cat ' + FILENAME + ' | clipboard';
					execCommand(cmd);
				})
				.catch(() => {
					console.error('文件写入失败')
				});
		})
	})
}

function getBase64FromLocal(Url, ImgType) {
	var imgData = fs.readFileSync(Url);

	var imgBase64 = Buffer.from(imgData).toString('base64');

	var imgBase64ForMarkdown = converseImgBase64WithPrefix(ImgType, imgBase64);
	
	writeStream(imgBase64ForMarkdown, FILENAME)
		.then(() => {
			var cmd = 'cat ' + FILENAME + ' | clipboard';
			execCommand(cmd);
		})
		.catch(() => {
			console.error('文件写入失败')
		});
}