When you call the parser you can pass options as following :

var reader = require('php-parser');
reader.parseCode('<?php echo true;', {
  parser: {
    debug: false, 
    locations: false,
    extractDoc: false,
    suppressErrors: false
  },
  lexer: {
    all_tokens: false,
    comment_tokens: false,
    mode_eval: false,
    asp_tags: false,
    short_tags: false
  }
});

• debug : enables debug output, useful for handling parsing errors when extending the library.
• locations : attach location nodes to AST - see more details
• extractDoc : extracting comments blocks - see more details
• suppressErrors: graceful parsing mode, when an error is raised it's ignored see more details

• all_tokens : extract all tokens (same output as token_get_all function in PHP)
• comment_tokens: extract also comments tokens (used when all_tokens is false)
• mode_eval: ignoring open or close tags, the input is directly a PHP script
• asp_tags: handles ASP like tags <% and %>
• short_tags : handle short opening tag <?