Hexadecimal colour values
This little trick avoids having to write a function to do the conversion.
The decimal system
The numbering scheme in everyday use is the decimal (or denary) system and numbers are represented by 10 digits i.e. the numbers 0 to 9.
Counting starts at zero, (see counting wheels below). Rotating the wheel anticlockwise adds 1 to the current count until the number reaches 9 whereupon the count is reset to 0.
Radians and degrees (or angular measure)
When measuring angles we usually
measure them in degrees. There are 360 degrees in a circle.
I.e. a degree simply divides a circle into 360 segments.
An alternative radial measure is known as a radian. A radian is the angle formed by measuring the radius around the circumference of a circle as show by the diagram. 1 radian is approximately 57.32 degrees.
The most common operators are mathematical operators; +, -, /, * (add, subtract, divide, multiply) for example. Operators can be split into two groups, comparison operators and assignment or 'action' operators. Comparison operators test to see if two variables relate to each other in the specified way, for example, one variable is a higher number than the other. Other operators perform an action on a variable, such as increasing it by one.
With decimal numbers, 12e+4 may be used to replace 12x104 and 12e-4 may be used to replace 12x10-4 etc.
The String object is used to manipulate a stored piece of text. String objects are created with new String().
A string literal is 0 or more characters enclosed in either double, or single quotes. For example
"Hello World" 'Sun wind and rain' "123"
Strings are a fundamental to any programming language and as well as all the comparison operators strings may be concatenated (joined) together using the concatenation operator, the plus symbol ( + ). for example
Ternary if statement
This provides a shorthand way to assign different values to a variable, depending on a condition.
var myVariable = document.getElementById("color").value myVariable == "red" ? 1 : 0;
This is identical to:
The following function performs the same test using the switch case statement. As you can see it is much more compact and consequently easier to read.