Solution Review: Validate Arguments

var concat = function(string1, string2) {
  
	if (typeof string1 === 'undefined' && typeof string2 === 'undefined') {
    throw new TypeError('Both arguments are not defined')
	}
  
  else if(typeof string1 === 'undefined'){
			throw new TypeError('First argument is not defined');
	}	
	
  else if(typeof string2 === 'undefined') {
		throw new TypeError('Second argument is not defined');
	}
  if(typeof string1  != "string" || typeof string2 != "string"){
        throw new TypeError('not string')
  }
	return string1 + string2;
}
console.log(concat("a","b"))
try{
  console.log(concat("a"))
}
catch(e)
{
  console.log(e)
}
try{
  console.log(concat(1,2))
}
catch(e){
  console.log(e)
}
try{
  console.log(concat(undefined,"bd"))
}
catch(e){
  console.log(e)
}
try{
  console.log(concat())
}
catch(e){
  console.log(e)
}