$ php composer.phar install
PHP's phar extension is missing. Composer requires it to run. Enable the extension or recompile php without --disable-phar then try again.
I trying the extension html2wiki (Unsupported) of mediawiki, where I need to install the composer to make it work.
My php version is: 7.0.13 and my question is
How to enable this extension https://pecl.php.net/package/phar