Question

For this homework I have to write a javascript code to validate the birth year is greater than 1870 and less than the current year plus one how can I combine them to show the same error message?

function isYearofBirthValid(birth) {
  "use strict";
  var alert = "";
  if(birth.length < 1870 && birth.length > 2013) {    <---- this part?
     alert("invalid year");
     return false;
  }
     return true;
}

Answer 1

Try this if statement instead:

function isYearofBirthValid(birth) {
    if(birth < 1870 || birth > 2013){
        alert("invalid year");
        return false;
    }
    return true;
}

Or if you actually want to look up what the next year is

function isYearofBirthValid(birth) {
    if(birth < 1870 || birth > new Date().getFullYear()+1){
        alert("invalid year");
        return false;
    }
    return true;
}

Then you call the function like so

var valid = isYearofBirthValid(1978); //valid = true