As I delve into the world of THREE.js, one thing that caught my attention is how object colors are specified using 0x followed by a hex value. What exactly does this signify?
Can these be considered valid variable names?
What is the mechanism behind their functionality?
I've always thought that variables cannot start with a number, so how does this fit into coding conventions?
Absolutely! You have the option to use hexadecimal notation for value literals. According to information from MDN - Numeric Literal:
Hexadecimal
To represent a hexadecimal number, you start with a leading zero followed by either a lowercase or uppercase Latin letter "X" (0x or 0X). If any digits following 0x fall outside the range of characters (0123456789ABCDEF), it will result in a SyntaxError saying: "Identifier starts immediately after numeric literal".
0xFFFFFFFFFFFFFFFFF // Represents 295147905179352830000 0x123456789ABCDEF // Equals to 81985529216486900 0XA // Equivalent to 10
You can refer to the grammar details here as well: http://www.ecma-international.org/ecma-262/5.1/#sec-7.8.3
(Interestingly, octal literals are not mentioned here due to their exclusion in Strict Mode. The related grammar rules can be found under B.1.1)
Can these be considered legitimate variable names?
No, they do not meet the criteria for valid variable names as they are actually integer literals. For example, instead of using 0x000000, you could simply use 0, and in place of 0x10, you can use 16.
One interesting fact about JavaScript is that it inherited the concept of specifying numeric constants from its predecessor, C, and even further back.
Typically, decimal constants in JavaScript are represented like this:
x = 42
In the past, and sometimes even today, there was a need to specify constants in octal form by adding an extra leading 0 like so:
x = 052 /* 42 */
With the introduction of hexadecimal constants, a leading 0x was added (which would have been incorrect syntax in previous versions):
x = 0x2a /* 42 */
Modern versions of JavaScript now also allow for binary constants (0b) and clearer octal constants (0o):
x = 0b101010 /* 42 */
x = 0o52 /* 42 */
It's important to note that none of these formats can be used as variable names.
Every hue corresponds to a specific numerical value rather than a variable, thus:
The color black is denoted by 0, displayed in hexadecimal as 0x000000.
What is the significance of having a hex value at the end of "0x"?
The presence of a hex value indicates that the numbers are represented in hexadecimal format, as explained in this resource.
Can these be considered valid variable names?
It depends on which specific ones you are referring to. If you mean those starting with "0X," they typically denote hexadecimal values; otherwise, please provide more details for clarification.
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