Native JS json tarball decompression

decompress.js

const { unzipSync } = require( 'zlib' );

const firstIndexOf = ( c, ...vars ) => Math.min( ...vars.map( v => c.indexOf( v ) ).filter( n => n > -1 ) );
const lastIndexOf = ( c, ...vars ) => Math.max( ...vars.map( v => c.lastIndexOf( v ) ) );

/**
 * Decompress JSON
 *
 * Reads a gzipped tarball (.tar.gz)
 * 1. Unzip it
 * 2. Convert all to utf-8
 * 3. Split files using the \0star separator
 * 4. Trim files until JSON markup start/end ({}) and JSON.parse
 *
 * Enjoy this 100% native tarball decompression!
 * @szanata ;)
 */
module.exports = raw => unzipSync( raw )
  .toString( 'utf-8' )
  .split( '\0ustar' )
  .slice( 1 )
  .map( c =>
    JSON.parse(
      c.substring( firstIndexOf( c, '{', '[' ), lastIndexOf( c, '}', ']' ) + 1 )
    )
  );