So there is the question of what operators are preformed first (operator precedence aka order of operations), and then also the direction in which they are preformed as well ( associativity ). To know if grouping with parentheses is really needed or not it is just a matter of know what comes first and to know that you just need to review what the precedence values are for each operator that is used an expression.
So Associativity is the direction in which operations are preformed such as left to right, or right to left. Operators like addition, subtraction and so forth have left to right associativity. However other operators such as the assignment, and logical not operator have right to left Associativity.
Here subtraction is an example of left to right associativity.
No matter what else is going on anything inside the parentheses or grouping if you prefer will be preformed first.
So logical or operators have left to right associativity. In addition of anything that comes along evaluates to true that will be the value of the expression any any additional parts will not effect the result. This effect is desirable in many situations as such it is often used as a way to feature test, and create poly fills.
I often seen Conditional operators used in expressions. When using them any expression that comes first will typically be preformed first because just about all other operators typically used to write expressions have higher precedence.
Say you want to estimate the amount of money that you might make for a blog post if you manage to rank at the top of a search engine result page. You know the score that a keyword of interest gets relative to a compare keyword to which you know the average money traffic. You also know what is average when it comes to click threw rates for the first position, second position and so forth, and also your average page revenue per mille.
So in order to figure estimates for amount of money you might make for each rang position you will need to work out some kind of lengthly expression and use that in a function in which you pass arguments for all of this.
So you might end up with something like this:
So getting back to the subject of this post the expression that is used in the pageMoney function is composed of operators that are all division and multiplication, both of which have the same operator precedence, as well as associativity. So for this expression the operations are just simply preformed from left to right.
Say you want to write a function that will spit out a value between zero and one from zero up to one and then back down again depending on a current frame index value compared to a total max frame count. These are the kinds of functions I end up writing when I am playing around with animations that are governed by logic that is writing in a functional, deterministic kind of way.
In this exercise I made a function that gives a value that behaves as expected and when doing so wrote several expressions that make use of a few operators including a native function call.
The particular expression of interest here is the one that returns the value between zero and one depending on the current state provided via the functions arguments. This expression was fairly easy for me to write because I have a decent grasp on order of operations these days, however in the past it would have taken a lot longer as I would have followed a kind of time consuming trial and error process.
So where I live I do not have and kind of hard wired broadband Internet access, just mobile broadband via my cell phone. So with my plan I only have so much high speed data until I get throttled down to 128kbps, as such I need to budget my data or pay out the node for a higher data cap.
With that in mind it would be nice to know a certain figure each day that will tell be if I am above or below budget when it comes to data. If I am above budget I can watch a video or two, if not I have to change my browsing habits and focus more on work which does not eat up a whole lot of data as I just need to push and pull text. So to write some kind of function that can help me get that data target figure I can exercise my knowledge of operator precedence to work out an expression that will do just that.