The JavaScript Diaries: Part 14/Page 2 | WebReference

# The JavaScript Diaries: Part 14/Page 2

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### Methods

 Name Description abs() Returns the absolute value of a number acos() Returns the arccosine (in radians) of a number asin() Returns the arcsine (in radians) of a number atan() Returns the arctangent (in radians) of a number atan2() Returns the arctangent of the quotient of its arguments ceil() Returns the smallest integer greater than or equal to a number cos() Returns the cosine of a number exp() Returns Enumber, where number is the argument, and E is Euler's constant, the base of the natural logarithms floor() Returns the largest integer less than or equal to a number log() Returns the natural logarithm (base E) of a number max() Returns the greater of two numbers min() Returns the lesser of two numbers pow() Returns base to the exponent power, that is, base exponent random() Returns a pseudo-random number between 0 and 1 round() Returns the value of a number rounded to the nearest integer sin() Returns the sine of a number sqrt() Returns the square root of a number tan() Returns the tangent of a number

#### Usage in Scripts

Let's see what we can do with some of these methods. (By now you can probably figure out these scripts without an explanation, so I won't go into greater detail. Instead, we'll focus on the methods themselves. Still, if a script begins to become complex, I'll stop and explain it. If you need further help, you can always e-mail me.)

#### Finding the Square Root

An obvious use is to find the square root of a number. Here's a basic script for doing the calculation:

This then would be called by the following, placed in the `body` of the document:

#### Rounding Numbers

Another calculation we could perform would be to round off a number. This script uses the code we wrote previously to find the circumfrence of a circle.

You could also use the `round()` method to set the number of decimal places:

The formula for rounding a number to `x` decimal points is:

 multiply the original number by 10^x (10 to the power of x) apply `Math.round()` to the result divide result by 10^x

Keep in mind that the format is as follows:

 `Math.round(10*x)/10;` (rounds to tenths) `Math.round(100*x)/100;` (rounds to hundredths) `Math.round(1000*x)/1000;` (round to thousandths)

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