Data Types
Data Types are very important concept in any programming language similarly in JavaScript as well. Variables are use to hold different data types according to the requirement.
<script>
var a = a + "codesFamily";
document.write(a); 
</script>
<script>
var x;
x = 10;
x = "codesFamily.";
document.write(x); 
</script>
<script>
  var name = "codesFamily"; //using Double quotes
  var name = 'codesFamily'; //using Single quotes
</script>
<script>
    var x = 10;
    var y = 20;
    document.write(x);
    document.write(y); 
</script>
<script>
    var x = 10;
    var y = 10;
    var z = 5;
    document.write(x == y); // return true
    document.write(' ',x == z); // return false
</script>
<script>
    var n = [1, 2, 3, 4];
    document.write(n[1]); 
</script>
<script>
  var emp = {
    firstName: "coed",
    lastName: "family"
  };
    document.write(emp.firstName + " " + emp.lastName); 
</script>