The with statement establishes a default object for a set of statements.
If there are any unqualified names in a set of statements, JavaScript first checks the default object to see if they exist there as properties of that object; otherwise a local or global variable is used.
with(beer)
{
if(percent_proof < 5)
document.write("Call this a strong beer?!");
else
document.write("This is what I call a beer!");
}
In this example the default object is 'beer' and the code displays one of two messages depending on the value of the property 'percent_proof'.