ZIP Extractor

Web app for browsing online zip files, without having to download the complete file.

Run locally:

npx zip-extractor

or download and:

./zip-extractor.js

Online demo: https://www.ting.st/zip-extractor.html

It uses HTTP Range requests to fetch parts of the file, like:

0. HEAD ─────────────────────────> file.zip
         <────Content-Length────╯  ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
                                   ┃ PK\3\4 Local file header 1  ┃<─╮
                                   ┃   2344 bytes                ┃  │
                                   ┃   chapter1.txt              ┃  │
                                   ┃   [compressed data]         ┃  │
1. GET ───────────────────────╮    ┠─────────────────────────────┨  │
   Range: last bytes before   │   ⎧┃ PK\3\4 Local file header 2  ┃<─│─╮
          content-length      │   ⎪┃   3210 bytes                ┃  │ │
                            ╭─│──>⎨┃   chapter2.txt              ┃  │ │
                            │ │   ⎩┃   [compressed data]         ┃  │ │
                            │ │    ┠─────────────────────────────┨  │ │
2. GET ───────────────────╮ │ │    ┃ ...                         ┃  │ │
   Range: [central        │ │ │    ┠─────────────────────────────┨  │ │
           dir offset,    │ │ │   ⎧┃ PK\1\2 Central dir header 1 ┃<─│─│─╮
           offset + size] │ │ │   ⎪┃   2344 bytes                ┃  │ │ │
                          ╰─│─│──>⎨┃   chapter1.txt offset───────╂──╯ │ │
                            │ │   ⎪┃ PK\1\2 Central dir header 2 ┃    │ │
 O                          │ │   ⎪┃   3210 bytes                ┃    │ │
/|\                         │ │   ⎪┃   chapter2.txt offset───────╂────╯ │
/ \                         │ │   ⎩┃ ...                         ┃      │
                            │ │    ┠─────────────────────────────┨      │
3. GET ─────────────────────╯ │   ⎧┃ PK\5\6 End of central dir   ┃      │
   Range: [entry offset,      ╰──>⎨┃   Central dir entry count   ┃      │
           offset + size]         ⎪┃   Central dir size          ┃      │
                                  ⎩┃   Central dir offset────────╂──────╯
                                   ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛