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JavaScript JavaScript Functions Arrow Functions Testing for Number Arguments

Is this solution acceptable?

check this solution, please.

const random = (upper, lower) => typeof(upper,lower) === 'number' ? Math.floor(Math.random() * (upper - lower + 1)) + lower : `That's not a number`

console.log(random(20, 10))

4 Answers

Steven Parker
Steven Parker
231,269 Points

You can only use "typeof" on one thing at a time.

If I try "console.log(random(20, "Joe"))" I get "That's not a number"
But if I try "console.log(random("Joe", 10))" I just get "NaN"

Steven Parker, but it worked, try it on the console?

Steven Parker
Steven Parker
231,269 Points

See the examples added to my answer.

Steven Parker, Yep, you rightπŸ‘

I think this is interesting as to the difference between isNaN() and typeof X === 'number'. [I figure they must be different or why would both exist?]

I wrote a similar logic with typeof before watching the solution. To explore the difference I changed my upper number check to isNaN and ran the following code:

const randomNumber = (lower, upper) => {
  if (typeof lower !== 'number' || isNaN(upper)) {
    throw Error('parameters are not both numbers');
  }
  return Math.floor(Math.random() * (upper - lower + 1)) + lower;
};

console.log(randomNumber(2, '4')); // 4 as a string is coerced/considered a number

console.log(randomNumber('two', 4)); // 'two' does NOT get coerced/considered a number - throws error

PS Like your use of a ternary Mytech T. More concise than mine.