In JavaScript, the modulus operator % returns the remainder of a division operation. When the dividend (the number being divided) is negative, the result of the modulus operation can be a bit confusing.
The modulus operator in JavaScript follows the sign of the dividend, which means that if the dividend is negative, the result will also be negative. Here’s an example:
-10 % 3 // returns -1
We can add our own modulo method to JavaScript which always gives the right answer rather than getting it wrong the way JavaScript does for negative numbers.
Number.prototype.mod = function(n) {
return ((this%n)+n)%n;
}JavaScript modulus negative example
Simple example code of how you could use the mod the method in a complete JavaScript code:
<!DOCTYPE html>
<html>
<body>
<script>
// Define the mod method on Number.prototype
Number.prototype.mod = function(n) {
return ((this % n) + n) % n;
}
let x = 7;
let y = -7;
let z = 12.5;
console.log(x.mod(3));
console.log(y.mod(3));
console.log(z.mod(5));
// Use the mod method in a conditional statement
if (x.mod(2) === 0) {
console.log("x is even");
} else {
console.log("x is odd");
}
</script>
</body>
</html>
Output:
We also use the mod method in a conditional statement to check if x is even or odd.
Comment if you have any doubts or suggestions on this JS module topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version