Memory efficient way of taking in data from an http request that needs to be written to EEPROM?

The code to generate the string is generated on the Espruino too - an import and an export function. But it does seem to work:

leds.export = function (type,index) {
  console.log(type);
	try {
		var eep=eepromtype[type][0];
		var off=eepromtype[type][1]+eepromtype[type][2]*index;
      var lenh=(eepromtype[type][2]/2); //one of the types has length 128 bytes, too long to handle with one call to .apply(), but all are even, so dividing in half is safe. 
      console.log(off);
		var rv= String.fromCharCode.apply(null,(eep.read(off,lenh)));
      rv+= String.fromCharCode.apply(null,(eep.read(off+lenh,lenh)));
      return btoa(rv);
	} catch (err) {
      console.log(err);
		return "";
	}
	
};

leds.import = function (type,index,data) {
	try {
		var eep=eepromtype[type][0];
		var off=eepromtype[type][1]+eepromtype[type][2]*index;
		eep.write(off,E.toUint8Array(atob(data)));
		return 200;
	} catch (err) {
		return 400;
	}
};

Thanks!

And yeah, I was getting it confused with .map(), and had forgotten you could pass multiple arguments to String.fromCharCode(). Been writing too much C lately.