Espruino, build query string from object

espruino_query_string.js

function queryString( a ) {
  var prefix,
    s = [],
    add = function( key, value ) {
      value =  value === null ? "" : value;
      s[ s.length ] =  key  + "=" + value;
    };
    var buildParams = function( prefix, obj, add ) {
      var name;
      if ( Array.isArray( obj ) ) {
        obj.forEach( function( v, i ) {
            buildParams( prefix + "[" + ( typeof v === "object" ? i : "" ) + "]", v,  add );
        });

      } else if ( typeof obj === "object"  ) {
        for ( name in obj ) {
          buildParams( prefix + "[" + name + "]", obj[ name ], add );
        }

      } else {
        // Serialize scalar item.
        add( prefix, obj );
      }
    };

  if ( Array.isArray( a )) {
    a.forEach( function( value, key) {
      add( key, value );
    });

  } else {
    for ( prefix in a ) {
      buildParams( prefix, a[ prefix ], add );
    }
  }

  return s.join( "&" );
}

Description

A function that builds query string from objects like jQuery#param function does.
The output value will be like arg1=1&arg2=hoge&arr[]=text&arr[]=22&arr[]=44.

Usage

var a = { hoge: 1, aba: "piyo", arr: ["ab",3, 4], eee: "1" };
queryString( a );
// arg1=1&arg2=hoge&arr[]=text&arr[]=22&arr[]=44