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Determine Odd / Even Numbers using JavaScript

This is how you can determine odd / even numbers using JavaScript.

By the way, I have a tutorial on it so make sure to check that out

Top comments (6)

If you care about performance, it’s actually quicker to use a bitwise test:

const isOdd = i => i&1 const isEven = i => 1&i^1 

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I’m a passionate Developer and Team Leader, I get excited by others successes. My downtime is filled with Social Dancing and Wilderness Backpacking.

I’ve never really understood bitwise operators.

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I’m a passionate Developer and Team Leader, I get excited by others successes. My downtime is filled with Social Dancing and Wilderness Backpacking.

Nifty! What other ways might you determine if a number is even or odd?
How might you use this to determine if a number is divisible by 5?

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To Determine number is divisible by 5, you can try

let number = 150 if(number % 5 === 0) console.log(`$number> is divisible by five`) >else console.log(`$number> is not divisible by 5`) > // Output: 150 is divisible by five 

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I’m a passionate Developer and Team Leader, I get excited by others successes. My downtime is filled with Social Dancing and Wilderness Backpacking.

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👨‍💻 Software Developer 📝 Tech Writer @LogRocket @get_livecycle 📹 Content Creator All things tech and programming 💻

Works like a charm I use this code often when trying to separate odd from even.

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Report even or odd number in JS

Many different methods can be used to let JavaScript work with events: HTML event attributes can execute JavaScript code directly HTML event attributes can call JavaScript functions You can assign your own event handler functions to HTML elements You can prevent events from being sent or being handled I’m trying to do the following exercise: Create a function that takes an integer as an argument and returns «Even» for even numbers or «Odd» for odd numbers.

Report even or odd number in JS

I’m trying to do the following exercise: Create a function that takes an integer as an argument and returns «Even» for even numbers or «Odd» for odd numbers.

Here is my code; I can’t figure out what I’m missing:

function even_or_odd(n) < if(n % 2 === 0) < console.log('Even'); >else < console.log('Odd'); >>; 

You are not returning anything, just outputing it in the console.

function even_or_odd(n) < if(n % 2 === 0) < return 'Even'; >else < return 'Odd'; >>; 

Assuming «i» is the number to check.

Nothing just return the string if returning is the goal:

 function even_or_odd(n) < if (n % 2 === 0) < return 'Even'; >else < return 'Odd'; >>; alert(even_or_odd(5)); alert(even_or_odd(2));

If anybody looking for shorthand using es6, They can try this-

const evenOrOdd = number => number % 2 ? 'Odd' : 'Even'; // Outputs- evenOrOdd(2) // Even evenOrOdd(3) // Odd 

JavaScript for Loop, JavaScript supports different kinds of loops: for — loops through a block of code a number of times. for/in — loops through the properties of an object. for/of — loops …

Javascript Program to Check if a Number is Odd or Even

In this example, you will learn to write a JavaScript program to check if the number is odd or even.

Even numbers are those numbers that are exactly divisible by 2 .

The remainder operator % gives the remainder when used with a number. For example,

const number = 6; const result = number % 4; // 2 

Hence, when % is used with 2 , the number is even if the remainder is zero. Otherwise, the number is odd .

Example 1: Using if. else

// program to check if the number is even or odd // take input from the user const number = prompt("Enter a number: "); //check if the number is even if(number % 2 == 0) < console.log("The number is even."); >// if the number is odd else

Enter a number: 27 The number is odd.

In the above program, number % 2 == 0 checks whether the number is even . If the remainder is 0 , the number is even.

In this case, 27 % 2 equals to 1 . Hence, the number is odd.

The above program can also be written using a ternary operator .

Example 2: Using Ternary Operator

// program to check if the number is even or odd // take input from the user const number = prompt("Enter a number: "); // ternary operator const result = (number % 2 == 0) ? "even" : "odd"; // display the result console.log(`The number is $.`);

Enter a number: 5 The number is odd. 

JavaScript Timing Events, These time intervals are called timing events. The two key methods to use with JavaScript are: setTimeout ( function, milliseconds) Executes a function, after …

JavaScript Events

HTML events are «things» that happen to HTML elements.

When JavaScript is used in HTML pages, JavaScript can «react» on these events.

HTML Events

An HTML event can be something the browser does, or something a user does.

Here are some examples of HTML events:

• An HTML web page has finished loading
• An HTML input field was changed
• An HTML button was clicked

Often, when events happen , you may want to do something.

JavaScript lets you execute code when events are detected.

HTML allows event handler attributes, with JavaScript code , to be added to HTML elements.

In the following example, an onclick attribute (with code), is added to a element:

Example

In the example above, the JavaScript code changes the content of the element with >

In the next example, the code changes the content of its own element (using this .innerHTML ):

Example

JavaScript code is often several lines long. It is more common to see event attributes calling functions:

Example

Common HTML Events

Here is a list of some common HTML events:

Event	Description
onchange	An HTML element has been changed
onclick	The user clicks an HTML element
onmouseover	The user moves the mouse over an HTML element
onmouseout	The user moves the mouse away from an HTML element
onkeydown	The user pushes a keyboard key
onload	The browser has finished loading the page

The list is much longer: W3schools javascript Reference HTML DOM Events .

JavaScript Event Handlers

Event handlers can be used to handle and verify user input, user actions, and browser actions:

• Things that should be done every time a page loads
• Things that should be done when the page is closed
• Action that should be performed when a user clicks a button
• Content that should be verified when a user inputs data
• And more .

Many different methods can be used to let JavaScript work with events:

• HTML Event Attributes can execute JavaScript code directly
• HTML event attributes can call JavaScript functions
• You can assign your own event handler functions to HTML elements
• You can prevent events from being sent or being handled
• And more .

You will learn a lot more about events and event handlers in the HTML DOM chapters.

Javascript — how to check if indexOf is even or odd?, Simplest and most efficient way of determining if a number is even or odd: You will need to loop through the array to get the index. Using that, you …

How to find even numbers?

I am trying to find even numbers from 0 to 100 but it is not working. even it not showing any error. can anyone help me to figure out?

I wouldn’t check for even numbers. It’s easier to just start by 0 and add 2 each iteration.

It stops after the firs round, because «if (x % 2 == 0)» does not match and else is a «break»

It breaks out of your while loop like ivar said

JavaScript Events, JavaScript lets you execute code when events are detected. HTML allows event handler attributes, with JavaScript code, to be added to HTML elements. With …

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5 способов для определения оdd / even в web-приложении

В статье будут рассмотрены 5 способов для для определения четности / нечетности строки в цикле. В качестве языка для примеров взят javascript. Некоторые из способов полностью переносимы в любые другие языки.

Способ #1

Этот способ, пожалуй, самый распространенный. Его можно встретить во всевозможных примерах, мануалах. Основывается он на четности и нечетности чисел (проверяем остаток от деления на двойку).

var type = i % 2 != 0 ? 'odd' : 'even'; 

Способ #2

Следующий способ основывается на простом математическом правиле — минус на минус дает плюс, плюс на минус — минус. На практике встречается реже чем первый, но все-таки встречается.

var tmp = -1; / . / var type = (tmp *= -1) > 0 ? 'odd' : 'even'; 

Способ #3

Данный способ определяет четность / нечетность простой проверкой бита.
В реальных проектах такого способа я не встречал, но все же он работает.

Способ #4

Этот способ примитивен, его принцип заключается в том, что бы присваивать переменной типа boolean обратное значение в цикле. На практике встречается очень редко.

var odd = true; / . / var type = odd ? 'odd' : 'even'; odd = !odd; 

Способ #5

Следующий способ основывается на css и для меня является приоритетным для использования. Не поддерживается только IE 7-8.

div:nth-child(odd) < color: red; >div:nth-child(even)

Возможно, кто-то использует какой-нибудь свой оригинальный способ и захочет им поделиться. Пишите, добавлю в статью

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Hiding odd rows in a table on click event

Your JavaScript is OK, but beware of writing code where you can get away without it. In this case, there is a CSS3 :nth-child() selector 1 that lets you select odd rows without tagging them manually with class=»hide» .

You just have to trigger the CSS rule when the button is pressed. Note that if you want to select one specific element in a document, it’s better to mark it using id=»…» and select it using document.getElementById(…) — that’s exactly what it is designed to do, and browsers will optimize ID lookups to be as fast as possible.

/* hideOddRows.js */ document.getElementById('HideRows').onclick = function hideRows()

table.odd-rows-hidden tr:nth-child(odd)

     
 
 
row 1
 
 
row 2
 
 
row 3
 
 
row 4
 
 
row 5
 
 
 
Hide Odd Rows   

1 Caveat: requires Internet Explorer ≥ 9. If you need to support older versions of IE, you’ll probably want jQuery.

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