How to find odd numbers in JavaScript

JavaScriptHow to find odd numbers

JavaScript is a dynamically typed scripting language that is widely used in Web development. As an important programming language, JavaScript has many features and grammatical structures, including odd number calculations.

In JavaScript, odd numbers can be found in many ways. Below, we will introduce these methods one by one and illustrate them with examples.

1. Use the modulo operator

The modulo operator (%) can return the remainder of the division of two numbers. Because the remainder of an odd number divided by 2 must be 1, and the remainder of an even number divided by 2 must be 0, we can determine parity by using the modulo operation on the number to be determined.

The following is an example of using the modulo operator to determine odd numbers:

function isOdd(num) {
  return num % 2 !== 0;
}

console.log(isOdd(3)); // 输出 true
console.log(isOdd(4)); // 输出 false

2. Using bit operators

The bit operator can be used to compare the binary value of the value. bit to operate. In JavaScript, using the bitwise operator bitwise negation (~) will convert a value to its opposite and then subtract 1, but for odd numbers and even numbers, the last digit of their binary digits is different (the last digit of the odd number One bit is 1, and the last bit of an even number is 0), so we can determine whether a value is odd by bitwise inversion.

The following is an example of using bitwise operators to determine odd numbers:

function isOdd(num) {
  return (num & 1) === 1;
}

console.log(isOdd(3)); // 输出 true
console.log(isOdd(4)); // 输出 false

3. Using the remainder function of the Math module

In JavaScript, the Math module provides The function that takes the remainder is called remainder(). We can call this function to find the remainder after dividing a value by 2 to determine whether the value is an odd or even number.

The following is an example of using the Math module to find the remainder function to determine odd numbers:

function isOdd(num) {
  return Math.abs(num % 2) === 1;
}

console.log(isOdd(3)); // 输出 true
console.log(isOdd(4)); // 输出 false

4. Use the AND operator

And operator (&) can Bitwise AND the binary representations of two values. For odd numbers and even numbers, the last digit of their binary digits is different (the last digit of odd numbers is 1, and the last digit of even numbers is 0), so we can judge this by ANDing a value with 1 Is the value odd or even?

The following is an example of using the AND operator to determine odd numbers:

function isOdd(num) {
  return (num & 1) === 1;
}

console.log(isOdd(3)); // 输出 true
console.log(isOdd(4)); // 输出 false

Summary:

The four methods mentioned above can all be used to determine odd numbers in JavaScript. Different methods may have different applicable scenarios, and developers can choose the method that best suits them according to their own circumstances. It is recommended that you focus on basic syntax when studying, so that you can better understand and use the characteristics of JavaScript.

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