Here's a 1-1 port in JavaScript https://github.com/benjamingr/js-restructure

    function matcher(obj) { "use strict";
      let props = Object.getOwnPropertyNames(obj);
      const re = new RegExp(props.reduce((p, c) => p + (c.startsWith("_") ? obj[c] : `(${obj[c]})`), ""));
      props = props.filter(x => !x.startsWith("_"));
      return function(pattern) { 
      let o = {};
      const res = re.exec(pattern);
      for(let i = 0; i < res.length; i++) o[props[i]] = res[i+1];
        return o;
      };
    }

And example usage:

```js matcher({ _ : "^", user : "\\w+", _2 : "@", host : "[^@]+", _3 : "$" })("user@ycombinator.com") ```