12.4. The Math Object

JavaScript provides several built-in objects, which can be called directly by the user. One of these is the Math object, which contains more than the standard mathematical operations (+, -, *, /).

In the previous sections, we learned how to construct, modify, and use objects such as giraffe. However, JavaScript built-in objects cannot be modified by the user.

Unlike other objects, the Math object is immutable.

12.4.1. Math Properties Are Constants

The Math object has 8 defined properties. These represent mathematical constants, like the value for pi (π) or the square root of 2.

Instead of defining a variable to hold as many digits of pi as we can remember, JavaScript stores the value for us. To use this value, we do NOT need to create a new object. By using dot notation and calling Math.PI, we can access the value of pi.

Example

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console.log(Math.PI);
console.log(Math.PI*4);
console.log(Math.PI + Math.PI);

Console Output

3.141592653589793
12.566370614359172
6.283185307179586

As stated above, the properties within Math cannot be changed by the user.

Example

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console.log(Math.PI);

Math.PI = 1234;

console.log(Math.PI);

Console Output

3.141592653589793
3.141592653589793

To use one of the other constants stored in Math, we replace PI with the property name (e.g. SQRT2 stores the value for the square root of 2).

12.4.2. Other Math Properties

Besides the value of pi, JavaScript provides 7 other constants. How useful you find each of these depends on the type of project you need to complete.

More powerful uses of the Math object involve using methods, which we will examine next.