If you try to declare a variable that already exists, JavaScript will
treat it as a simple assignment statement and assign any new value in
the declaration statement to the variable. If the duplicate declaration
has no assignment, then nothing happens. If you try to assign a value to
a non-existent variable, JavaScript will create the variable for you.
<script type="text/javascript">
//Commented lines starting with the double
//First we will declare a few variables
//and assign values to them
myTxt = "Do IT";
mynum =13;
//Note that myTxt is a string and mynum is numeric.
//Next we will display these to the user.
document.write(myTxt);
//To concatenate strings in JavaScript, use the '+' operator
document.write("My favourite number is "+ mynum);
</script>
<script type="text/javascript">
//Commented lines starting with the double
//First we will declare a few variables
//and assign values to them
myTxt = "Do IT";
mynum =13;
//Note that myTxt is a string and mynum is numeric.
//Next we will display these to the user.
document.write(myTxt);
//To concatenate strings in JavaScript, use the '+' operator
document.write("My favourite number is "+ mynum);
</script>
