Unobtrusive event handlers

http://stackoverflow.com/questions/21658563/why-these-two-functions-dont-want-to-run/

by hibbard_eu

HTML

<form id="myForm">
    <label for="firstName">First Name:</label>
    <input type="text" name="input" id="firstName" size="20">
    <br/>
    <label for="lastName">Last Name:</label>
    <input type="text" id="lastName" size="20" value="enter your name here">
    <input type="button" id="check" value="Check!">
</form>

JavaScript

var firstName = document.getElementById("firstName"),
    lastName = document.getElementById("lastName"),
    checkButton = document.getElementById("check");

firstName.onblur = function(){
  if (this.value === ""){
    alert("please enter your name");
    this.focus();
  }  
}

check.onclick = function(e){
    e.preventDefault();
    if (lastName.value === "enter your name here") {
      alert("enter your last name");
      lastName.focus();
    }
}