The term "expression", in JScript, refers to a string that a human being
would read as a Boolean or mathematical expression. (Expressions contain
symbol characters like "+" rather than words like "added to".)
EXAMPLES:
var oneExpression = "3 * (4 / 5)";
var aSecondExpression = "Math.PI * radius * 2";
var aThirdExpression = aSecondExpression + "%" + oneExpression;
var aFourthExpression = "(" + aSecondExpression + ") % (" + oneExpression + ")";
Eval() is a special function that evaluates any legitimate JScript
expression and returns the result.
EXAMPLES:
var anExpression = "6 * 9 % 7";
var total = eval(anExpression); // Assigns the value 5 to the variable total.
var anotherExpression = "6 * (9 % 7)";
total = eval(anotherExpression) // Assigns the value 12 to the variable total.
var totality = eval("...surrounded by acres of clams."); // Generates an error.