javascript - 如何让jszip生成相同的缓冲区

Question

这是代码

import JSZip = require('jszip');
import crypto = require('crypto');

let zip = new JSZip();

zip.file("hello.txt", "Hello World\n");
zip.folder("nested").file("hello.txt", "Hello World\n");

zip.generateAsync({
    type: 'nodebuffer',
    mimeType: 'application/epub+zip',
    compression: 'DEFLATE',
    compressionOptions: {
        level: 9
    },
})
    .then(buf => {
        const md5 = crypto.createHash('md5');
        let result = md5.update(buf).digest('hex');

        console.dir(result);
    })
;

如果运行此代码两次，将得到 diff md5

当上下文相同时，如何使其成为相同的缓冲区

Answer 1

问题在于 JSZip 创建的 .zip 存档条目将具有与其关联的文件修改时间戳。这会导致不同时间生成的文件之间存在微小差异(通常是几个字节)。因此，我们需要手动指定文件时间戳，并确保在 .zip 存档中仅创建虚拟文件夹。

这种方法应该适合您(每次给出相同的 MD5 哈希值):

import JSZip = require('jszip');
import crypto = require('crypto');

// You must fix the date (set to the same value) so that the zip archive timestamps will be equal.
// Also we must create virtual folders or they will be assigned timestamps too, resulting in a different hash.
const options = { date: new Date('2019-07-24 06:00:00Z'), createFolders: false};
zip.file("hello.txt", "Hello World\n", options);
zip.file("nested/hello.txt", "Hello World\n", options);

zip.generateAsync({
    type: 'nodebuffer',
    mimeType: 'application/epub+zip',
    compression: 'DEFLATE',
    compressionOptions: {
        level: 9
    },
})
    .then(buf => {
        const md5 = crypto.createHash('md5');
        let result = md5.update(buf).digest('hex');
        console.dir(result);
    })
;