Data Types in Javascript

In JavaScript, every number data type is treated as a floating-point number. A floating-point number is a number that includes a decimal place. For example, the fraction one-half wouldn't be written as .5, but as 0.5. Multiply that 0.5 by 6.1234 (or any number, really), and the decimal (the "point") will have "floated" to a new position within the new number. Hence the term "Floating Point". Because of this floating-point capability, JavaScript is great to use with numbers. Combine this with its loosely typed nature and you get a very easy to use and flexible yet powerful programming language.

Within the Numbers data type, there are a few different variations that must be addressed. Understanding these variations is crucial to your skill in working with them. As with most concepts within JavaScript, they are easy to understand. Along with the different number types are several built in number values that can be used within your scripts. The different types and built in values are as follows.

Integers

An integer is a number that exists without a decimal place. It is a whole number. For example, the number 5 would be an integer, but the number 5.5 would not be due to the existence of a decimal place. An integer may be positive or negative. An integer may be stated as a decimal, octal, or hexadecimal number. The below list explains what is meant by the terms decimal, octal, and hexadecimal.

• Decimal - A decimal number is any number that exists with a base number of 10. The decimal number is what we (humans) use in every day numbering. It is represented by the numbers (or combinations of) 0 to 9.
• Hexadecimal - A Hexadecimal number is a number that exists with a base number of 16. The hexadecimal numbering system is widely used within the computing industry because a large value may be stated using a small amount of numbers. It is represented by the numbers 0 to 9 (which represent the decimal numbers 0 to 9) and the letters A to F (which represent the decimal numbers 10 to 15). A hexadecimal number must begin with 0x or 0X when stated within JavaScript. An example of a hexadecimal number stated within JavaScript is 0XFF that represents the decimal number 255.
• Octal - An Octal number is a number that exists with a base number of 8. The Octal numbering system isn't used within the computer industry as much as the hexadecimal numbering system, but it still finds some applications. It is represented by the numbers 0 to 7 and is stated within JavaScript with a zero following the actual number value. For example, the number 6 in octal must be stated as 06. An example of an octal number stated within JavaScript is 077 that represents the decimal number 63.

You'll get a feel for thinking in these differing number systems with some practice. Don't feel discouraged if you don't catch on quickly. Thinking in a number system other than ten is extremely difficult for a human.

Floating Point Numbers

As explained earlier, a floating-point number is a number that contains a decimal. A Floating-point number may also be expressed through the means of exponential notation. An exponential number may be expressed with the base number followed by an e or E, followed by the power you wish to raise the number to. For example, the number 8 may be expressed as the decimal number 2 raised to the third power as such: 2E3.

Built In Values

There are a number of different built in values you may have a use for. Use these values with the Math object to achieve your desired result. You'll learn more about the Math object later, for now what is important now is that you know they exist. The different built in values are as follows.

• Math.E - This represents the base of natural logarithms, also called Euler's Constant, which is 2.718281828459045 as a decimal floating point number.
• Math.LN2 - This represents the value for the natural logarithm of 2, which is 0.6931471805599453 as a decimal floating-point number.
• Math.LN10 - This represents the value for the natural logarithm of 10, which is 2.302585092994046 as a decimal floating point number.
• Math.LOG2E - This represents the value for the base 2 of the log of E. E represents Euler's Constant, which is 2.718281828459045 as a decimal floating point number.
• Math.LOG10E - This represents the value for the base 2 of the log of E. E represents Euler's Constant, which is 2.718281828459045 as a decimal floating point number.
• Math.PI - This represents the value of PI, which is 3.141592653589793 as a decimal floating point number.
• Math.SQRT2 - This represents the square root of 2, which is 1.4142135623730951 as a decimal floating-point number.
• Math.SQRT1_2 - This represents the square root of one half, which is 0.7071067811865476 as a decimal floating- point number.

You may use the above Math functions alone or together within your JavaScript functions. For a more detailed look at each of the above Math object properties, see the JavaScript Language Reference, Object Properties. Special Values

JavaScript has provided five different properties of the Number object to further its capabilities as a math intensive language. They are quite common in the world of mathematics, but not so common in the world of programming. They are as follows.

• Number.MAX_VALUE - This property is used to return the largest number possible available to JavaScript. This number is 1.7976931348623157e+308.
• Number.MIN_VALUE - This property is used to return the smallest number possible available to JavaScript. This number is 5e-324, which is five to the negative 324, which is 5 with 324 zeros in front of it, then a decimal point.
• Number.NaN - This property is used to signify that the value is NaN, which stands for Not A Number. It simply has no other value but NaN. It is equal to no other number, including itself.
• Number.POSITIVE_INFINITY - The POSITIVE_INFINITY property is returned when a calculation returns a number greater than the largest Positive number available to JavaScript, which is 1.7976931348623157e+308.
• Number.NEGATIVE_INFINITY - The NEGATIVE_INFINITY property is returned when a calculation returns a negative number greater than the largest negative number available to JavaScript, which is 5e-324.

You may use the above Number functions alone or together within your JavaScript functions. For a more detailed look at each of the above Number object properties, see the JavaScript Language Reference, Object Properties.