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jay read
2,580 PointsIs there anything wrong doing it this way
Forget the fact that I haven't written the conditional statements yet. The way I have written the random number generator is different to the video, I would like to know if my way i still efficient. function getRandomNumber(val1, val2){
return Math.floor(Math.random() * val2 + val1); }
2 Answers
Steven Parker
229,657 PointsIt's a matter of operation, not efficiency. Your function is certainly efficient, but it does something different from the one in the video.
The video function takes two arguments, a lower limit and an upper limit, and generates a number between them (inclusive).
Your function takes two arguments also, but the first one is a lower limit and the second one is a range. It will generate a number somewhere within the range but offset by the limit.
So your version works, but in a different way, so it's not a solution to the challenge posed in the video.
Luis Marsano
21,425 PointsIt's wrong.
For example, for any integer x, your getRandomNumber(x, 0) always evaluates to x.
Not very random.
Your getRandomNumber(-1, 0) never returns 0, and it sometimes should.
Steven Parker
229,657 PointsThe original formula could also be made to not be random with certain arguments. But both will generate a random number between 1 and 10 if called like: "getRandomNumber(1, 10)".
Luis Marsano
21,425 PointsSteven Parker On the contrary, yes, it would. A correct implementation has an equal chance for getRandomNumber(-1, 0) to return -1 or 0. Not so with the one proposed here, since for integer x, getRandomNumber(x, 0) = Math.floor(Math.random() * 0 + x) = x.
Steven Parker
229,657 PointsYes, but as I said the first time, the arguments of the function shown above do something different from the one in the video.
Luis Marsano
21,425 PointsI'm not contradicting your point, simply providing a definite example. Counterexamples are typically how generalizations are disproved, like the generalization that the proposed function is correct, i.e., always agrees with the function from the video. A counterexample proves the contrary: not all evaluations are correct.