Comparing equality of two numbers using JavaScript Number() function

Question

When I try to compare two numbers using JavaScript Number() function, it returns false value for equal numbers. However, the grater-than(">") and less-than("<") operations return true.

var fn = 20;
var sn = 20;

alert(new Number(fn) === new Number(sn));

This alert returns a false value. Why is this not returns true?

Rayon · Accepted Answer · 2023-10-02 05:29:55Z

21

new Number() will return object not Number and you can not compare objects like this. alert({}==={}); will return false too.

Remove new as you do not need to create new instance of Number to compare values.

var fn = 20;
var sn = 20;

alert(Number(fn) === Number(sn));

edited Oct 2, 2023 at 5:29

answered Mar 18, 2016 at 6:42

Rayon

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Parash · Accepted Answer · 2020-12-10 01:45:25Z

2

If you are using floating numbers and if they are computed ones. Below will be a slightly more reliable way.

console.log(Number(0.1 + 0.2) == Number(0.3)); // This will return false.

To reliably/almost reliably do this you can use something like this.

const areTheNumbersAlmostEqual = (num1, num2) => {
    return Math.abs( num1 - num2 ) < Number.EPSILON;
}
console.log(areTheNumbersAlmostEqual(0.1 + 0.2, 0.3));

answered Dec 10, 2020 at 1:45

Parash

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