Check if numbers in JavaScript is in the range of int in Java (–2147483648 < n < 2147483647)

Question

What's he correct way to validate JavaScript numbers as Java int?

  –2147483648 < n < 2147483647

 IsNumeric(2147483648) --> true: which is > int
 parseInt("2147483648") --> 2147483648 : which is > int

Answer 1

Assuming that the range of integers in Java is actually "–2147483648 <= n <= 2147483647", the expression ((+a)|0) == a will work as specified.

• +a evaluates the expression a as a number;
• |0 converts the number to 32-bit integer

The comparison will fail, when a is not exactly representable by an 32-bit integer.

Answer 2

Just test the number in an if?

var number = 1234567;
if (Number.isInteger(number)) && number > -2147483648 && number < 2147483647)
{
    console.log("It is a valid integer!");
}

Answer 3

as a function :

function isValidInt32(number){
   return Number.isInteger(number) && number > -2147483648 && number < 2147483647; 
}

Answer 4

isInt32(state) {
    if(!(/^([+-]?[1-9]\d*|0).[0]$/.test(state))
        && !(/^([+-]?[1-9]\d*|0)$/.test(state))) {
        return false;
    }
    const view = new DataView(new ArrayBuffer(32));
    view.setInt32(1, state);
    return Number.parseInt(state) === view.getInt32(1);
}