scv/lib/actions/cssactions.js

SCV前端工程自动化工具，工作流

/**
 * 提供css文件的相关流操作
 */
const path = require('path');
const sutil = require('../sutil');
const css = require('css');
const CleanCSS = require('clean-css');

module.exports = cssActions;

/**
 * css类型的文件操作,比如校验,合并,压缩等
 * @param  {object} actions watchitem中的actions项
 * @return {boolean}    through stream
 */
function cssActions(actions){
	return function (file, encoding, cb) {
	    let opStr = file.contents.toString();
	    // 校验
		if (actions.hint) {
			let msg = '\taction:hint...';
			let errs = cssHint(opStr,actions.hint);
			if (errs.length>0) {
				sutil.log(msg +'x');
				errs.forEach(function(err){
					sutil.log('\terror no:'+err.line+'\tmsg:'+err.reason);
				});
	    		// return false;  终止流
			}else{
				sutil.log(msg+'✔');
			}
		}
		// prefix
		if (actions.prefix) {
			let msg = '\taction:prefix...';
			let result = cssPrefix(opStr,actions.prefix);
			if (typeof result== 'string') {
				sutil.log(msg+'✔');
				opStr = result;
				file.contents = new Buffer(opStr,encoding);
			}else{
				sutil.log(msg +'x')
				sutil.log('\terror msg:'+result.message);
				// return false;
			}
		}
		// 压缩
		if (actions.compress) {
			let msg = '\taction:compress...';
			let result = cssCompress(opStr,actions.compress);
			if (typeof result== 'string') {
				sutil.log(msg+'✔');
		        file.contents = new Buffer(result,encoding);
		      }else{
				sutil.log(msg +'x')
		        if(Array.isArray(result)){
		        	result.forEach(function(err){
						sutil.log('\terror no:'+err.line+'\tmsg:'+err.reason);
		        	});
		        }
		        // return false;  终止流
		      }
		}
	  	cb(null,file);
	 };
}
/**
 * css字符串的语法校验hint操作,使用css插件的hint方法
 * @param  {string} str  源码字符串
 * @param  {object} opt  css插件hint方法的配置参数,其中slient项恒为true
 * @return {[error]}
 */
function cssHint(str,opt){
	opt = typeof opt ==='object'?opt:{};
	opt.silent = true;
	let ast = css.parse(str,opt);
	return ast.stylesheet.parsingErrors;
}

/**
 * css压缩操作
 * @param  {string} str	 要操作的样式字符串
 * @param  {object} opt  clean-css插件方法的配置参数
 * @return {string|Error} 压缩过的字符串,失败则错误数组  
 */
function cssCompress(str,opt){
	opt = typeof opt ==='object'?opt:{};
	try{
		// let css = require('css');
		// let ast = css.hint(str,{silent:true});
		// return css.stringify(ast,opt);
 		let result = new CleanCSS(opt).minify(str);
 		if (result.errors.length==0) {
 			return result.styles;
 		}
 		return result.errors;
	}catch(e){
		return [e];
	}

}

/**
 * css3语法规则增加浏览器私有前缀
 * @param  {string]} str 源css字符串
 * @param  {string} opt autoprefixer插件的参数
 * @return {string|[error]}  
 */
function cssPrefix(str,opt){
	opt = typeof opt ==='object'?opt:{
								cascade: false,
								browsers:['last 10 version', 'safari 5','ie > 8', 'opera 12.1', 'ios 6', 'android 2.3']
                };

	let postcss = require('postcss');
	let autoprefixer = require('autoprefixer');
	try{
		let prefixer = postcss([ autoprefixer(opt)]);
		let result = prefixer.process(str);
		return result.css;
	}catch(e){
		return e;
	}
}