How Can I Fix the Unexpected Behavior of JavaScript\'s Modulo Operator with Negative Numbers?

Fixing Negative Numbers Modulo Operator in JavaScript

In JavaScript, the modulo operator (%) returns the remainder when dividing one number by another. However, for negative numbers, JavaScript's modulo operator behaves unexpectedly, returning a negative result. This issue arises because JavaScript internally uses signed integers, which are not suitable for modulo operations.

To resolve this issue, you can use the following custom mod function:

Number.prototype.mod = function (n) {
  "use strict";
  return ((this % n) + n) % n;
};

This function ensures that the modulo result is always positive, consistent with the mathematical definition of modulo.

Usage:

console.log(-13.mod(64)); // Output: 51

Explanation:

The custom mod function first calculates the remainder using the native JavaScript modulo operator. Then, it adds the divisor (n) to the remainder. This ensures that the result is non-negative. Finally, it performs a second modulo operation to get the final positive remainder.

This modified modulo function aligns JavaScript's behavior with the expected mathematical result, facilitating consistent and accurate calculations involving negative numbers.

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