Page 158 - DCAP202_Fundamentals of Web Programming

Unit 13: Building Object of JavaScript

13.1 Using JavaScript as a Scientific Calculator Notes

JavaScript’s Math object provides advanced arithmetic and trigonometric functions, expanding
on JavaScript’s basic arithmetic operators (plus, minus, multiply, divide). The Math object in
JavaScript is borrowed from Java. In fact, the implementation of the Math object in JavaScript
closely parallels the Math class in Java, except that the JavaScript Math object offers fewer
methods.
JavaScript’s Math object properties are treated as constants. In fact, the property names are in all
upper-case, following the usual convention of capitalizing variable constants. These properties
return often-used values, including pi and the square root of 2. The Math methods are used in
mathematical and trigonometric calculations.

Notes Handy Math-object methods include ceilings, floor,paw, exp (exponent), max, min,
round, and random. (Random is only available when using the X Window platform,
however.)
The Math object is static, so you don’t need to create a new Math object in order to use it. To access
the properties and method of the Math object, you merely specify the Math object, along with
the method or property.

Example: To return the value of pi, you use:
var pi = Math. PI;
Similarly, to use a math method you provide the name of the method, along with the parameters
to use.

Example: To round the value of pi, you’d use:
var pi = Math.PI;
var pieAreRound = Math.round(pi); // displays
JavaScript does not recognize the keywords PI and round all by themselves. Exception: you may
use with statement to associate the names of methods and properties with the Math object.

Did u know? This technique is a handy space-saver when you must use several.
The previous example can be written as
With (Math)
{
var pi = PI; Notes
var pieAreRound = round(pi);
alert (pieAreRound)
}
13.1.1 JavaScript Objects for a Date

The Date object is useful when you want to display a date or use a timestamp in some sort of
calculation. In Java, you can either make a Date object by supplying the date of your choice, or

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