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• I was looking for this quotation.
• However, the book seems to be not exists.

• Example of writing 13 with binary number.

• Volatile memory is RAM (Random Access Memory).
• Non - volatile memory is hard disk.
• Modern computer has more than 30 billion bits in volatile data storage. I think this means RAM, right?

• Every set of bits has a role.
• This role is what it is data type in higher level programming language.
• In JavaScript there are these 6 types of basic values.
  • Function.
  • Number.
  • Object.
  • String.
  • Undefined value.
    • Undefined.
    • Null.

* To create value, in JavaScript, you can just invoke its name.

• JavaScript engine usually has its own memory allocation algorithm.
• Nevertheless, the only problem would be if you need all variables to be exists at the same time.
• In case not, variable's memory block will be "rotated" accordingly as it is in the memory allocation algorithm.

• There used to be a problem with accidentally overflowing the value of a variable.
• Especially in 8 bits or 16 bits computer.
• Today computer is at least 32 bits to 64 bits.
• There should be no problem on dealing larger variable's value.

• The positivity of a number (whether it is positive or negative number) as well as decimal point are stored on another block of memory.
• Hence, float and negative float number need more memory blocks.
• The maximum number of decimal points can be stored with JavaScript (this paragraph does mention whether this is meant for computer or JavaScript in general) is 9 quadrillion (15 trailing zeros), which is still good for most program written in JavaScript.

• Here is an example of exponent notation.
• For example, 2.999e8 means 2.999*10^8.
• For example, 2.999e-8 means 2.999*10^-8.

• For number with infinite amount of trailing numbers behind comma, like for example pi.
• The ideal case would be an approximation.
• So, programmers need to be careful when dealing with decimal numbers. The best is to make an approximation of those numbers.

• Operators are most of the time is a symbol.
• Mathematics operator like +, -, ....
• There are these kinds of operator.

• Each operators in any programming language has its own order of magnitude.
• The larger the more priority it has over the lower ones.
• If there are operators with same priority the left will be executed first.
• These all means the basic mathematics equation on which one should be calculated first addition or multiplication.

• So when designing a statement you need to make sure the order of the operators you would like to happen first.
• Then, assign bracket appropriately.
• Actually, just try to put everything in bracket for you to make sure that the operator will happen after the others.

• There is infinity and -infinity to represent positive and negative infinity.
• Anything happen to infinity will still be infinity, perhaps the negative or the positive change. There are these examples.
  • infinity + 1 is still infinity.
  • infinity - 1 is still infinity.
  • However, I am still not sure on what will be for infinity/-infinity. Will this be -1?
• These numbers are not mathematically solid.
• Do not use this, if possible.
• There are little to no use for the programmer to use this, but if this comes from a result of a calculation.

• NaN is stand for "not a number".
• NaN is used to represent a result that is not meaningful.
• These are an example of operations those will return null.
  • 0/0 will return NaN.
  • Infinity - Infinity will return NaN.
• Any operation that is not meaningful will return as a NaN in JavaScript.
  • In other programming language this could be a Math error.
  • This is actually the thing that I do not like from JavaScript.
  • NaN does not return error. So, sometimes it is hard to debug a mathematical based animation.

• Newlines is what it is when you press Enter key in your keyboard while typing something.
• String (or text) in JavaScript should be put in a line.
• You cannot put a line break in a string directly by pressing Enter.
• Instead you should use \n to imply line break to the JavaScript interpreter.

• Escaping character is a character that will not be included in the quoted text (string).
• In JavaScript or any general programming language (Python included) the escaping character is \.

• Above are examples of escaping character to incites line break as well as string operation.
• There is only one operator that can be used to do string operator which is +.
• + if there are at least one parameter is a string. Then type coercion will happen. This, will make the whole operation to be string concatenation.

• Unary operation is an operation that take one parameter.
• Usually unary operation takes the right side of th operator to be its parameter.
• Whereas binary operation takes what it is in the left and the right of the operator.
  • For example, 1 + 2 is a binary operator.
  • That operation will take 1 and 2 as its parameter.
• An example of unary operation is typeof which to return a string of the parameter's type data.
• Another example of unary operation is - and !. These are use to inverse numbers and boolean respectively.

• Here are another example of binary operator.
• This time this is a operator for comparison.
• Comparison operator will return a boolean value (whether it is true or false).

• From the above paragraph, I know that string can also be compared.
• Every character has its own Unicode and string comparison will compare between these Unicode.
• Good thing to mention is that lower case is larger than upper case.
• For example, a > Z will return true.
• The Unicode standard applied to any symbol you see in your computer.
• These includes Arabic, Chinese, Cyrillic, Japanese, ....
• When comparing string, JavaScript goes from the left to right and go step - by - step in increasing index.

• NaN == Nan will be false, although both value is the same.
• NaN is the only value in JavaScript that will return false when compared to itself.

• NaN, in JavaScript, is used to determine the result of nonsensical computation.
• And as such it does not equal to other nonsensical results.

• Unary operation ! or not, is used to flip the value of boolean.
• For example, !false will be true.

• Knowing all the operation.
• The most important thing when programmer tries to make a statement is to take care which one is more operators has more priority then the other.
• For example this below is a valid JavaScript operation.

1 + 1 == 2 && 10 * 10 > 50

• The programmer needs to define which operators will happen first.
• Otherwise, to make sure and for safety you can also bind the operators and the parameters in a brackets of ().

• So, based on above paragraph.
• Mathematical operations will happen first.
  • So these means all of those, %, *, +, -, /.
    • But each has its own priority that otherwise will be taken from left to right.
    • For example * will happen first, then -.
  • The next priority is those comparison operator: >, <, >=, <=, ==, !=, ===, !==.
  • Then "and" operation &&.
  • Then "or" operation ||.

• There is only one ternary operation in JavaScript which is used for conditional value assignment.
• Ternary operation is operation that takes 3 parameters.
• These are the examples.

console.log(true ? "hello" : "world") // Will print "hello" in the console.
console.log(false ? "hello" : "world") // Will print "world" in the console.

• The previous point is a conditional operation.
• The value on the left of the question mark will assign a boolean comparison.
• The value on the left of ":" will be assigned if the boolean comparison is true.
• The value on the right of ":" will be assigned if the boolean comparison is false.

• Many operation in JavaScript do not produce meaningful value.
• In JavaScript this will be shown as null or undefined.

• null and undefined are an accident during the JavaScript development.
• In most of the time these values do not matter.
• But for me, I define undefined as if I have a variable but I have not yet to put a value in it.
• null will be used to define an "empty" variable that used to have value.

• I you have concern on the operator's priority, then it is the best solution to have each operations within a bracket. Thus, you can assign the priority properly.

• Example of automatic type conversion in JavaScript.
• This is what it means to be programming/scripting language with type coercion.

• When something does not mapped properly to a number or a boolean in an obvious way, a NaN will be the result.
• For example, "five" - "four" will be NaN (I think, I have not yet try this, in any cases I hope you get my point).

• So overall, in case JavaScript programmer find a NaN bug, they need to see on potential type coercion.
• Usually NaN happen because of division by 0 or unwanted type coercion.

• Type coercion exists when comparing values.
• Example of valid type coercion within comparison operator.
  • "" == false will return true.
  • 0 == false will return true.
  • NaN == false will return true.
  • null == 0 will return true.
  • null == undefined will return true.
• You can use comparison to know if your data is valid.
• For example, you can use "" == false to check the validity of string.

• In order to prevent type coercion when comparing value, in JavaScript you can use === or !==.
• Both operators are binary operator.
• Both operators mean as a strict comparison operator.

• It is recommended in JavaScript to have all comparison to be in strict comparison.
• So you are sure that both type and the value are the same (or not).

• Be careful, in JavaScript there are comparison operator that can act as a value validator.
• These operators are || and &&.
• The || is used to take the left parameter if the left parameter is valid and take the right parameter if the left parameter is invalid.
• I would call the || as a left valid checker.

• This technique is called "short - circuiting logical operator".

• The && is a left invalid checker.
• The && will check left parameter is invalid then return that value.
• For both || and && will try to return the left value if the left value satisfy the condition.

• If the condition is satisfied already, then there will be no check on the right parameter.

• The conditional operator (the only ternary operation JavaScript has) works in similar way.
• The first value is checked if it it true than the operation end without checking another value.

• Value in JavaScript is inferred by typing its name directly.
• For example, true, null or the arbitrary values, like 13 or "abc".
• You can combine or transform value with operator.
• Learning what operators are available is a crucial part when learning a programming/scripting language.

• The conclusion for this chapter.