issue with checking all element type of an Array in Javascript

Question

I am trying to check all the element type of an array in javascript. I am actually writing a function which whould only accept an array with numbers.

so

[1,2,-3,-4,0]  //valid input
[1,2,-3b,-4a,0]  //Invalid input

I am trying to achieve the following by using every() function of javascript as follows,

try {
                    if (!inputArr.every(x => typeof x === 'number')) {
                           throw 'input array should only have numbers';
                    }
                }
                catch (err) {
                    return err;
                }

but getting error. when I investigate it further than realized that,

typeof 1 // number
typeof 1a // error

so there is no way we can check the type of a alphanumeric value. can someone please suggest some options here. I am using pure javascript ES5 Or ES6.

@Manatax But isNaN("123") would return false, even though "123" is not a number. If that suits OP's needs, then it would work. If the goal is a stricter check, then typeof seems like the way to go. — Michael Geary
– Michael Geary, Commented Jun 29, 2017 at 1:21
@Manatax, I need to check strictly that supplied input array has all the numbers ONLY. isNan will not work here as mentioned by @ Michael Geary — Akash
– Akash, Commented Jun 29, 2017 at 1:50
Since [1,2,-3b,-4a,0] is invalid syntax, and your program would not even run, should we assume that the input is a kind-of array represented as a string, as in "[1,2,-3b,-4a,0]"? — user663031
– user663031, Commented Jun 29, 2017 at 2:42
@Akash Wait, are you saying the input to your function is a string, not an array, and the string may be something like "[1,2,-3a,4]"? That is a whole different question. I would first use JSON.parse() to attempt to convert this string to a JavaScript array. If it throws an exception, then you had something like the "-3a" in it and should reject. Otherwise, run your test loop on the resulting array. — Michael Geary
– Michael Geary, Commented Jun 29, 2017 at 4:15

user663031 · Accepted Answer · 2017-06-29 02:44:29Z

2

[1,2,-3b,-4a,0] is invalid syntax, and your program would not even run. Therefore, we will assume that the input is a string, as in "[1,2,-3b,-4a,0]". In that case:

function check(input) {
  try {
    const array = JSON.parse(input);
    return array.every(x => typeof x === 'number');
  } catch(e) {
    return false;
  }
}

answered Jun 29, 2017 at 2:44

user663031

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