jz-img-compress/util.js

压缩项目中的图片资源的自动化工具

const path = require('path');
const fs = require('fs');
const crypto = require('crypto');

/**
 * 遍历给定目录下的指定文件
 * @param {String} root 根目录
 * @param {Function} filter 过滤器
 * @returns {[String]}
 */
function travelPaths(root, filter) {
    let paths = [];

    const entries = fs.readdirSync(root, { withFileTypes: true });

    let filepath;
    for (const entry of entries) {
        filepath = path.join(root, entry.name);
        if (entry.isFile() && filter(filepath)) {
            paths.push(filepath);
        } else if (entry.isDirectory()) {
            paths.push(...travelPaths(filepath, filter));
        }
    }
    return paths;
}

/**
 * 检测是否是图片文件(目前 tinypng.com 只支持 png/jpg/jpeg 类型的图片)
 * @param file
 */
function isImage(file) {
    return ['.png', '.jpg', '.jpeg'].includes(path.extname(file))
}

/**
 * 计算文件md5
 * @param file
 * @returns {string}
 */
function fileHash(file) {
    const buffer = fs.readFileSync(file)
    return crypto.createHash('md5').update(buffer).digest('hex')
}

/**
 * 解析缓存
 * @param {string} cacheFile 缓存文件位置
 */
function resolveCache(cacheFile) {
    let cache = []
    if (fs.existsSync(cacheFile)) {
        const content = fs.readFileSync(cacheFile).toString('utf8')
        if (content) {
            cache.push(...JSON.parse(content))
        }
    }
    return cache
}

/**
 * 覆盖缓存
 * @param data 缓存数据
 * @param {string} cacheFile 缓存文件位置
 */
function overrideCache(data, cacheFile) {
    // 检查缓存文件是否存在
    if (!fs.existsSync(cacheFile)) {
        fs.mkdirSync(path.dirname(cacheFile), {recursive: true})
    }

    fs.writeFileSync(cacheFile, data, {flag: 'w'})
}

function output(results) {
    const originSize = results.filter(r => r.type === 'compressed').reduce((size, item) => size + item.originSize, 0)
    const compressedSize = results.filter(r => r.type === 'compressed').reduce((size, item) => size + item.compressedSize, 0)
    const msg = `
====> 本次压缩结果汇总 <====
处理文件总数: ${results.length}
缓存命中数: ${results.filter(r => r.type === 'ignore').length}
实际压缩文件数: ${results.filter(r => r.type === 'compressed').length}
原始文件总大小: ${(originSize / 1000).toFixed(2)}kB
压缩文件总大小: ${(compressedSize / 1000).toFixed(2)}kB
压缩率: ${((originSize - compressedSize) / originSize * 100).toFixed(2)}%`
    console.log(msg)
    console.log()
}

module.exports = {
    travelPaths,
    isImage,
    fileHash,
    resolveCache,
    overrideCache,
    output,
}