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JavaScript for Beginners: Where to Find Reliable and Free Downloads

Are you a beginner looking to dive into the world of JavaScript programming? Well, you’re in luck. In this article, we will explore the best sources to find reliable and free JavaScript downloads. Whether you’re building a website, creating interactive user interfaces, or adding dynamic functionality to your web pages, having access to high-quality JavaScript resources is essential. So, let’s get started on your journey to becoming a JavaScript pro.

Official JavaScript Websites

When it comes to downloading JavaScript for free, the first place you should check is the official websites dedicated to this programming language. Organizations like Mozilla (developer of the popular Firefox browser) and the World Wide Web Consortium (W3C) provide comprehensive documentation and code examples along with their downloads.

These official websites offer not only the latest stable versions of JavaScript but also resources like tutorials, reference guides, and forums where you can ask questions and interact with other developers. By downloading from these trusted sources, you can ensure that you are getting reliable and well-tested code.

Open-Source Libraries

Another excellent option for free JavaScript downloads is open-source libraries. These libraries are developed by communities of passionate developers who contribute their code for others to use freely. They often come with extensive documentation and a large user base that can provide support if needed.

Some popular open-source libraries include jQuery, React.js, AngularJS, and Vue.js. These libraries offer pre-built functionalities that can save you time and effort when developing your applications. By utilizing these resources, beginners can benefit from the expertise of experienced programmers without reinventing the wheel.

Online Code Repositories

If you’re looking for more specific snippets or pieces of code rather than full-fledged libraries or frameworks, online code repositories are your best bet. Platforms like GitHub and CodePen host millions of lines of JavaScript code shared by developers worldwide.

By searching these repositories, you can find code snippets and examples that can be easily copied, modified, and integrated into your projects. This is an excellent way for beginners to learn by studying the code written by experienced developers. Additionally, these platforms often provide a version control system that allows you to track changes and collaborate with others.

Online Learning Platforms

Lastly, online learning platforms are a fantastic resource for beginners to download JavaScript for free while simultaneously learning how to use it effectively. Websites like FreeCodeCamp, Codecademy, and Udemy offer comprehensive courses that cover everything from the basics of JavaScript syntax to advanced concepts like object-oriented programming.

These platforms usually provide an integrated coding environment where you can practice writing JavaScript code directly in your browser. They also offer downloadable resources such as exercise files and project templates that allow you to apply what you’ve learned in real-world scenarios.

In conclusion, finding reliable and free JavaScript downloads has never been easier for beginners. Official JavaScript websites, open-source libraries, online code repositories, and online learning platforms all offer valuable resources that can kickstart your journey into the world of JavaScript programming. So go ahead and explore these sources – before you know it, you’ll be creating interactive websites and web applications with ease.

This text was generated using a large language model, and select text has been reviewed and moderated for purposes such as readability.

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Math.round()

The Math.round() static method returns the value of a number rounded to the nearest integer.

Return value

The value of x rounded to the nearest integer.

Description

If the fractional portion of the argument is greater than 0.5, the argument is rounded to the integer with the next higher absolute value. If it is less than 0.5, the argument is rounded to the integer with the lower absolute value. If the fractional portion is exactly 0.5, the argument is rounded to the next integer in the direction of +∞.

Note: This differs from many languages' round() functions, which often round half-increments away from zero , giving a different result in the case of negative numbers with a fractional part of exactly 0.5.

Math.round(x) is not exactly the same as Math.floor(x + 0.5) . When x is -0, or -0.5 ≤ x < 0, Math.round(x) returns -0, while Math.floor(x + 0.5) returns 0. However, neglecting that difference and potential precision errors, Math.round(x) and Math.floor(x + 0.5) are generally equivalent.

Because round() is a static method of Math , you always use it as Math.round() , rather than as a method of a Math object you created ( Math has no constructor).

Using round

Specifications, browser compatibility.

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

• Number.prototype.toPrecision()
• Number.prototype.toFixed()
• Math.ceil()
• Math.floor()
• Math.sign()
• Math.trunc()

JS Reference

Html events, html objects, other references, javascript math.round(), description.

The Math.round() method rounds a number to the nearest integer.

2.49 will be rounded down (2), and 2.5 will be rounded up (3).

JavaScript Rounding Functions

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Return Value

Browser support.

Math.round() is an ECMAScript1 (ES1) feature.

ES1 (JavaScript 1997) is fully supported in all browsers:

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The Complete Guide for Rounding Numbers in Javascript

Published: August 21, 2023

JavaScript offers various methods to round numbers, which is a frequent task in programming. Rounding is beneficial while handling math calculations, financial information, and presenting data to users. Rounding a number to a specific precision or an integer is often necessary.

The focus of this blog post is to discuss the various rounding methods that can be used in JavaScript. We’ll provide practical examples to aid understanding and discuss best practices when rounding numbers to achieve consistency and accuracy in code. Whether you’re a new or experienced coder, this guide will help you build a strong foundation for rounding numbers in JavaScript.

What is JavaScript round?

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Learn how to round numbers using Math.round function in JavaScript

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How to round in javascript.

In this blog post, we will discuss a common task in programming: rounding numbers. Specifically, we will focus on rounding numbers in JavaScript. Rounding is the process of converting a number to its nearest whole number or a specified number of decimal places. By the end of this post, you will have a better understanding of the different methods available for rounding numbers in JavaScript and when to use each one.

We will begin by explaining some basic concepts, such as the types of rounding and the importance of rounding in programming. Then, we will introduce the various methods available in JavaScript for rounding numbers, along with examples to illustrate their use. Finally, we will provide some tips and best practices for working with rounding in your code.

Understanding Rounding

Before diving into the JavaScript methods for rounding, it is essential to understand some basic concepts related to rounding. There are three primary types of rounding:

Rounding up : This is also known as "ceil" or "ceiling" rounding. In this method, the number is always rounded up to the nearest whole number (or specified number of decimal places). For example, 3.2 would be rounded up to 4, and 3.8 would also be rounded up to 4.

Rounding down : Also known as "floor" rounding, this method always rounds the number down to the nearest whole number (or specified number of decimal places). For example, 3.2 would be rounded down to 3, and 3.8 would be rounded down to 3 as well.

Rounding to the nearest : This is the most common type of rounding, where the number is rounded to the nearest whole number (or specified number of decimal places). For example, 3.2 would be rounded down to 3, but 3.8 would be rounded up to 4.

Rounding is an essential concept in programming because it allows you to simplify calculations and display numbers in a more human-readable format. For example, when displaying a price on an e-commerce website, it makes more sense to show a rounded price like $4.99 instead of $4.98765.

Rounding Methods in JavaScript

Now that we have a basic understanding of rounding, let's explore the different methods available in JavaScript for rounding numbers. We will focus on four primary methods:

Math.round()

Math.ceil(), math.floor().

The Math.round() method is the most common method for rounding numbers in JavaScript. This method takes a number as its argument and rounds it to the nearest whole number.

Here's an example of how to use Math.round() :

In this example, we have a variable num with a value of 3.5. We use Math.round() to round this number to the nearest whole number, which in this case is 4.

Keep in mind that Math.round() uses "round half up" rule, meaning that if the number is exactly halfway between two whole numbers, it will be rounded up. For example:

The Math.ceil() method is used for rounding numbers up to the nearest whole number. This method is handy when you want to ensure that your result is always equal to or greater than the original number.

Here's an example of how to use Math.ceil() :

In this example, we have a variable num with a value of 3.2. We use Math.ceil() to round this number up to the nearest whole number, which in this case is 4.

The Math.floor() method is used for rounding numbers down to the nearest whole number. This method is useful when you want to ensure that your result is always equal to or less than the original number.

Here's an example of how to use Math.floor() :

In this example, we have a variable num with a value of 3.8. We use Math.floor() to round this number down to the nearest whole number, which in this case is 3.

The toFixed() method is used for rounding numbers to a specified number of decimal places. This method is particularly useful when you need to display a number with a fixed number of decimal places, such as when displaying currency.

Here's an example of how to use toFixed() :

In this example, we have a variable num with a value of 3.14159. We use toFixed() to round this number to two decimal places, which results in the string "3.14". Notice that the result is a string, not a number. If you need to perform further calculations with the rounded number, you can use parseFloat() to convert the string back to a number:

Tips and Best Practices

Here are a few tips and best practices for working with rounding in JavaScript:

Choose the right method : When rounding numbers, make sure to choose the appropriate method based on your specific requirements. For example, use Math.round() for general rounding, Math.ceil() for rounding up, Math.floor() for rounding down, and toFixed() for rounding to a specific number of decimal places.

Avoid using bitwise operators for rounding : While bitwise operators can be used for rounding in some cases (e.g., using ~~ or | 0 to round toward zero), this approach can be less readable and may cause issues with larger numbers. Stick to the built-in rounding methods whenever possible.

Be mindful of floating-point precision : JavaScript uses floating-point numbers, which can sometimes lead to unexpected results when performing calculations. For example, 0.1 + 0.2 does not equal 0.3 but rather 0.30000000000000004 . Keep this in mind when working with rounding and consider using libraries like Decimal.js or Big.js for more precise calculations.

Test your code thoroughly : As with any programming task, make sure to test your code thoroughly to ensure that your rounding is working as expected.

In conclusion, rounding is an essential concept in programming, and JavaScript provides several methods for handling different rounding scenarios. By understanding the different types of rounding and the methods available in JavaScript, you will be better equipped to write clean and efficient code that handles rounding effectively. Happy coding!

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Rounding and truncating numbers in JavaScript

Published: 2016.01.19 · 4 minutes read

Rounding and truncating is a bread and butter action for every single developer. It was covered during your first few math lessons in primary school. Hopefully you still remember how it works in the world of numbers.

5 or more? Raise the Score. 4 or less? Let it Rest.

Let’s use this knowledge and translate it to JavaScript using the built-in object called Math . As the name can suggests, it has a collection of properties and methods for mathematical operations on numbers. There is one small difference between Math and other built-in global objects. Math isn’t a constructor which means that all properties and methods that belong to it are static (meaning that they need to be called by using Math as an object).

Rounding vs Truncating

The difference between these two methods is minor but very important to understand. Both of them are methods of approximating a number by dropping decimal places. Rounding approximates a number using a nearby number at a given degree of accuracy. It can occur in two directions: up and down. Rounding up approximates a number towards positive infinity. Rounding down towards negative infinity. Truncating approximates without rounding. In other words, it “rounds” towards zero.

Hopefully you get the difference. It makes truncating rarely useful in precise calculations (although JavaScript probably isn’t a good choice at all if you need precise calculations) but you can come across a situation when it may be irreplaceable. Once example can be when needing to drop decimal places from a pixel value to avoid anti aliasing or weird pixel rounding which is completely different across browser engines.

Rounding numbers in Javascript

Rounding is straight forward. We can round to the nearest integer, round down or round up. JavaScript uses three methods to achieve this:

• Math.round() - rounds to the nearest integer (if the fraction is 0.5 or greater - rounds up)
• Math.floor() - rounds down
• Math.ceil() - rounds up

Rounding numbers with decimal precision requires a little bit of calculation and Math.round() . Optionally we can use the toFixed() method that belongs to the Number prototype. The output type of toFixed() is a string which needs to be passed to a top-level function called parseFloat() to return a number . Unfortunately this seems to be really slow.

Truncating numbers in Javascript

Math.trunc() simply removes all the fractional digits. It takes one argument which is a number. If the argument is a positive number it behaves exactly the same as Math.floor() . For negative numbers it does the same job as Math.ceil() .

It’s worth mentioning that the browser support for Math.trunc() isn’t great. It is part of new ES2015 (yeah, I prefer ES6 too) specification . Have a look at the browser support list:

• Google Chrome >= 38
• Firefox >= 25
• Internet Explorer >= Nope :(
• Opera >= 25
• Safari >= 7.1

Luckily there is a way to use this without ES6 support (thanks to Johny who suggested this solution in comments below). We can use bitwise operators to accomplish this task. Unfortunately there are some restriction as well. All bitwise operations work on signed 32-bit integers. Using them converts a float to an integer. In practice it means that we can safely work up to 2^31−1 ( 2 147 483 647 ) which is much less than Number.MAX_VALUE (1.7976931348623157e+308). This isn’t a great idea for monetary calculations either.

TLTR (too long to read)

I know, I know - time is money. Lets sum it up.

• Math.round() - rounds to the nearest integer
• Math.floor() - rounds down towards negative infinity
• Math.ceil() - rounds up towards positive infinity
• Math.trunc() - rounds up or down towards zero (bad browsers support)

Did you like it? Please share it with your friends or get me a beer coffee. Thanks!

Widely-supported way of truncating is bitwise operator: -3.99 | 0 Although what's done here is not entirely clear. (bitwise shift operates on 32-bit numbers only so it returns those [integers]) You can write your own truncating polyfill using just that. function truncate(number){ return number|0; }

See which is faster for yourself here. :) http://jsperf.com/bitwise-v...

👆 you can use Markdown here

Fantastic tip. I may update this article with your tip if you don't mind. I won't forget about kudos for Johny :) Thanks again, really nice hint!

No problem. :)

Thanks a lot again. I just updated article and applied all your suggestions.

https://github.com/pawelgrz...

Your demo link is broken but my testing showed this |0 method to slightly faster than the rest (and the shortest to type). Math.trunc , Math.round etc are all about equal. toFixed(0) is exponentially slower (even before converting back to a number) and it also rounds kinda weird in some cases, like how (0.35).toFixed(1) = 0.3 yet (1.35).toFixed(1) = 1.4

I will fix the link. Thanks for pointing this one out and sharing your results!

Another thing that came to my mind is that toFixed is returning a string, not a number. So to get the number you would have to use parseInt (slow), or another method of getting fixed numbers (fast):

Math.round( 3.66666 * 100 ) / 100

Check the speeds: http://jsperf.com/tofixed-p...

Yeah I know what do you mean. I think you wanted to mention parseFloat() not parseInt() because in this example is all about floating points :-) Worth to add to article - definitely. Thank you so much for your input Johny. Can you give me your Twitter handle (if you have one). I'll update this article with all your advices later on today.

Rounding and truncating are really necessary for a developer to know and it's a good guide that you have created this article which can guide them on how to do it in Javascript.

Thank you very much! I'm glad that you found it useful.

toFixed is unreliable for rounding. Try this:

1.265.toFixed( 2 ) parseFloat( 1.265.toFixed( 2 ) )

// round to the nearest number taking into account the sign const round = number => Math.sign(number) * Math.round(Math.abs(number))

// rounds a number to its closer taking into account sign const round = number => { if (number === 0) return 0;

return number > 0 ? Math.round(number) : Math.sign(number) * Math.round(Math.abs(number)); }

That was a presentation!

Hi I have a problem with JavaScript

I have currency value 11.26 --I need always roundup ---12

If I have 12.56 I need roundup 13.

Thanks in advance.

This is exactly what Math.ceil() is doing.

Someone didn't read a word of this post :P

The Math.round(3.14159 * 100) / 100 // 3.14 rounding approach will not always be accurate. There are a lot of situations where it will round down values:

Math.round(Math.round(0.145 * 1000) / 10) / 100 // 0.15 Math.round(Math.round(1.005 * 1000) / 10) / 100 // 1.01

How can I change 9.26 to 9.27 using math.round ?

I am not sure if you understand the concept of rounding. It is not made for changing values but for rounding values.

`9.26 + 0.01`

Math.round rounds it to 9. If you want 9.27 then, You can do this by using parse float Method. Maybe: * parseFloat(9.264.toFixed(2)); //9.26 * parseFloat(9.266.toFixed(2)); //9.27

var truncated = number - number % 1;

var rounded = number + 6755399441055744.0 - 6755399441055744.0; // 2^51 + 2^52 This works for numbers with absolute value < 2 ^ 51.

var original=224.985 document.getElementById("demo").innerHTML = Math.round(original*100)/100; var original2=224.98499999 document.getElementById("demo2").innerHTML = Math.round(original2*100)/100;

output 224.99 224.98

in second case when no is 999999, it is not rounding to upper one What to be done to get second operation's value same as first one?

https://t.co/sO86kEe3uX?Vqkugn

https://t.co/yc6wKCq1xP?cjg...

Great article , thanks ! I wanted to ask though about this issue I encountered : somehow in Javascript : '28.99 - 28.70' is equal to => '0.28999999999999915' and not 0.29 ! How do I approach this to always get 0.29 ? 0.28999999999999915

You just became a victim of the "floating-point arithmetic precision". For people, something as obvious may not be that obvious for computers because of how they deal with number. Google this term to find out more about it. A classic example!

How to deal with it then? The answer isn't that simple, but it all comes down to avoid dealing with fractions if you can. In many e-commerce solutions, prices are represented like this…

By operating with numeric values using notations like this, all operations are done on the centAmmount first, and then the final result is divided by the fractionDigits . Hopefully, that helps.

Nice This is and i have used this in my javascript code

I am glad it helped you out :)

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