By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. What is the fastest way to sum up an array in JavaScript? A quick search turns over a few different methodsbut I would like a native solution if possible.

This will run under SpiderMonkey. And with arrow functions introduced in ES6, it's even simpler:. This retrieves array. The optimization is made by caching the value. This is equivalent to a while reverse loop.

It caches the value and is compared to 0, thus faster iteration. For a more complete comparison list, see my JSFiddle. Note: array. I started a JSPerf for array summations. It was quickly constructed and not guaranteed to be complete or accurate, but that's what edit is for :. The fastest loop, according to this test is a while loop in reverse. Based on this test for-vs-forEach-vs-reduce and this loops.

Then comes forEach and reduce which have almost the same performance and varies from browser to browser, but they have the worst performance anyway. It performs faster when I test it on the browser with performance.

I think this is a better way. What do you guys think? I tried using performance. I took a very large array and found the sum of all elements of the array. I ran the code three times every time and found forEach and reduce to be a clear winner. Learn more. Fastest JavaScript summation Ask Question.

Asked 9 years, 6 months ago. Active 4 months ago. Viewed k times. Josh K. Josh K Josh K If you need to see what the fastest way to do something is, try out several, and measure the results. Chad: Well obviously, however I'm not in my "out of the box thinking" days.

Active Oldest Votes. You should be able to use reduce.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm trying to find a way to calculate the sum of all numbers between 1 to N using JavaScript. The following is the code I have tried so far but it doesn't seem to work.

I have tried using jslint and other validators online to check if I might have missed something but that doesn't seem to help me find the reason for the code not working either. Is there something that I'm missing above that's preventing the script from executing the addition?? I know this is already solved but I wanted to post a quick ES6 oneliner I wrote after reading this thread and explain it more thoroughly for others who like me don't have a solid math background.

It works because it uses a mathematic formula that Carl Friedrich Gauss came up with. Basically, whenever you are adding the sum of n numbers, you will have pairs in the sequence.

So Gauss figured out that you didn't need to loop through each pair and add them, instead you just need to add the middle pair and multiply that sum by the total number of pairs. This works really well for programming because they aren't looping through each number which in programming would eat through your resources.

You set your placeholder variable equal to one. You also set the number of iterations equal to the input variable. The do loop then adds your placeholder variable with 'i' and then the loop exits when it is no longer greater than 1, which is correct because you have your placeholder equal to one.

While this might not be the most optimal answer for the case of min:0 max:n, it might be the easiest to read and understand. Learn more.

Asked 5 years ago. Active 2 months ago.Help to translate the content of this tutorial to your language!

### Improvements

Recursion is a programming pattern that is useful in situations when a task can be naturally split into several tasks of the same kind, but simpler.

Or when a task can be simplified into an easy action plus a simpler variant of the same task. When a function solves a task, in the process it can call many other functions. A partial case of this is when a function calls itself. In other words, multiplies x by itself n times. So, the recursion reduces a function call to a simpler one, and then — to even more simpler, and so on, until the result becomes obvious.

Here we can rewrite the same using the conditional operator? The maximal number of nested calls including the first one is called recursion depth. In our case, it will be exactly n. The maximal recursion depth is limited by JavaScript engine. We can rely on it beingsome engines allow more, but is probably out of limit for the majority of them.

That limits the application of recursion, but it still remains very wide. There are many tasks where recursive way of thinking gives simpler code, easier to maintain.

The information about the process of execution of a running function is stored in its execution context. To do a nested call, JavaScript remembers the current execution context in the execution context stack. The process is the same for all functions:. The new current execution context is on top and boldand previous remembered contexts are below. When we finish the subcall — it is easy to resume the previous context, because it keeps both variables and the exact place of the code where it stopped.

The previous one is restored off the top of the stack:. The execution of pow 2, 2 is resumed. As we can see from the illustrations above, recursion depth equals the maximal number of context in the stack. Note the memory requirements.

Contexts take memory.

### How to Find the Sum of an Array of Numbers in JavaScript

In our case, raising to the power of n actually requires the memory for n contexts, for all lower values of n. The iterative pow uses a single context changing i and result in the process. Its memory requirements are small, fixed and do not depend on n. Any recursion can be rewritten as a loop. The loop variant usually can be made more effective. And the optimization may be unneeded and totally not worth the efforts. Recursion can give a shorter code, easier to understand and support.

A department may have an array of staff.

For instance, sales department has 2 employees: John and Alice. Or a department may split into subdepartments, like development has two branches: sites and internals. Each of them has their own staff. It is also possible that when a subdepartment grows, it divides into subsubdepartments or teams.

For instance, the sites department in the future may be split into teams for siteA and siteB.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here.

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. What is the fastest way to sum up an array in JavaScript? A quick search turns over a few different methodsbut I would like a native solution if possible.

This will run under SpiderMonkey. And with arrow functions introduced in ES6, it's even simpler:. This retrieves array. The optimization is made by caching the value. This is equivalent to a while reverse loop. It caches the value and is compared to 0, thus faster iteration. For a more complete comparison list, see my JSFiddle. Note: array. I started a JSPerf for array summations. It was quickly constructed and not guaranteed to be complete or accurate, but that's what edit is for :.

The fastest loop, according to this test is a while loop in reverse. Based on this test for-vs-forEach-vs-reduce and this loops. Then comes forEach and reduce which have almost the same performance and varies from browser to browser, but they have the worst performance anyway. It performs faster when I test it on the browser with performance.

I think this is a better way. What do you guys think? I tried using performance. I took a very large array and found the sum of all elements of the array. I ran the code three times every time and found forEach and reduce to be a clear winner.

Learn more. Fastest JavaScript summation Ask Question. Asked 9 years, 6 months ago. Active 4 months ago. Viewed k times. Josh K. Josh K Josh K If you need to see what the fastest way to do something is, try out several, and measure the results. Chad: Well obviously, however I'm not in my "out of the box thinking" days. Active Oldest Votes. You should be able to use reduce. ChaosPandion ChaosPandion Tim: Again, this is running under SpiderMonkey, not any particular browser.Get the latest tutorials on SysAdmin and open source topics.

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Become an author. Mathematical operations are among the most fundamental and universal features of any programming language. In JavaScript, numbers are used frequently for common tasks such as finding browser window size dimensions, getting the final price of a monetary transaction, and calculating the distance between elements in a website document. Although a high-level understanding of mathematics is not a prerequisite to being a capable developer, it is important to know what types of operations are available in JavaScript, and how to use math as a tool to accomplish practical tasks.

Unlike other programming languages, JavaScript only has one number data type ; there is no distinction made between integers positive or negative whole numbers and floats numbers with a decimal pointfor example.

In this tutorial, we will go over arithmetic operators, assignment operators, and the order of operations used with JavaScript number data types. Arithmetic operators are symbols that indicate a mathematical operation and return a value. JavaScript has many familiar operators from basic math, as well as a few additional operators specific to programming.

Addition and subtraction operators are available in JavaScript, and can be used to find the sum and difference of numerical values.

JavaScript has a built-in calculator, and mathematical operations can be done directly in the console. In addition to doing math with plain numbers, we can also assign numbers to variables and perform the same calculations. In this case, we will assign the numerical values to x and y and place the sum in z. Similarly, we use the minus sign - to subtract numbers or variables representing numbers.

One interesting thing to note and be aware of in JavaScript is the result of adding a number and a string. Instead of adding the two numbers, JavaScript will convert the entire statement into a string and concatenate them together. A common reason to use addition or subtraction in JavaScript would be to scroll to an id minus the height in pixels of a fixed navigation bar. Addition and subtraction are two of the most common mathematical equations you will use in JavaScript. Multiplication and division operators are also available in JavaScript, and are used to find the product and quotient of numerical values.

Division is particularly useful when calculating time, such as finding the number of hours in a quantity of minutes, or when calculating the percent of correct answers completed in a test.

One arithmetic operator that is slightly less familiar is the modulo sometimes known as modulus operator, which calculates the remainder of a quotient after division. As an example, we know that 3 goes into 9 exactly three times, and there is no remainder.

We can use the modulo operator to determine whether a number is even or odd, as seen with this function:. In the above example, 12 divides evenly into 2therefore it is an even number. Often in programming, modulo is used in conjunction with conditional statements for flow control. Exponentiation is one of the newer operators in JavaScript, and it allows us to calculate the power of a number by its exponent. Using the exponentiation operator is a concise way of finding the power of a given number, but as usual, it is important to keep consistent with the style of your code base when choosing between a method and an operator.

Increment and decrement operators increase or reduce the numerical value of a variable by one. Note that increment and decrement operators can only be used on variables; attempting to use them on a raw number will result in an error.

Increment and decrement operators can be classified as a prefix or postfix operation, depending on whether or not the operator is placed before or after the variable.

The value of x was increased by one. The value of y was not increased in the postfix operation. This is because the value will not be incremented until after the expression has been evaluated. Running the operation twice will then increment the value. The increment or decrement operator will be seen most often in a loop. In this for loop example, we will run the operation ten times, starting with 0and increasing the value by 1 with each iteration.At this point in the course we discuss math in JavaScript — how we can use operators and other features to successfully manipulate numbers to do our bidding.

Okay, maybe not. Some of us like math, some of us have hated math ever since we had to learn multiplication tables and long division in school, and some of us sit somewhere in between the two. But none of us can deny that math is a fundamental part of life that we can't get very far without. This is especially true when we are learning to program JavaScript or any other language for that matter — so much of what we do relies on processing numerical data, calculating new values, and so on, that you won't be surprised to learn that JavaScript has a full-featured set of math functions available.

In programming, even the humble decimal number system that we all know so well is more complicated than you might think. We use different terms to describe different types of decimal numbers, for example:.

We even have different types of number systems! Decimal is base 10 meaning it uses 0—9 in each columnbut we also have things like:. Before you start to get worried about your brain melting, stop right there!

This means that whatever type of numbers you are dealing with in JavaScript, you handle them in exactly the same way. But for the purposes of this course, we'll just worry about Number values. Let's quickly play with some numbers to reacquaint ourselves with the basic syntax we need. Enter the commands listed below into your developer tools JavaScript console.

Returns the remainder left over after you've divided the left number into a number of integer portions equal to the right number. Note : You'll sometimes see numbers involved in arithmetic referred to as operands. Note : You may sometimes see exponents expressed using the older Math.

For example, in Math. We probably don't need to teach you how to do basic math, but we would like to test your understanding of the syntax involved. Try entering the examples below into your developer tools JavaScript console to familiarize yourself with the syntax.

Let's look at the last example from above, assuming that num2 holds the value 50 and num1 holds the value 10 as originally stated above :.

As a human being, you may read this as "50 plus 10 equals 60"then "8 plus 2 equals 10"and finally "60 divided by 10 equals 6". But the browser does "10 divided by 8 equals 1.

**JavaScript Calculate 2 Numbers Form Input Text - Addition, Subtraction, Multiplication, Division**

This is because of operator precedence — some operators are applied before others when calculating the result of a calculation referred to as an expressionin programming. Operator precedence in JavaScript is the same as is taught in math classes in school — Multiply and divide are always done first, then add and subtract the calculation is always evaluated from left to right.

If you want to override operator precedence, you can put parentheses round the parts that you want to be explicitly dealt with first. So to get a result of 6, we could do this:. Note : A full list of all JavaScript operators and their precedence can be found in Expressions and operators. Sometimes you'll want to repeatedly add or subtract one to or from a numeric variable value. Note : These operators are most commonly used in loopswhich you'll learn about later on in the course.

For example, say you wanted to loop through a list of prices, and add sales tax to each one. You'd use a loop to go through each value in turn and do the necessary calculation for adding the sales tax in each case. The incrementor is used to move to the next value when needed. We've actually provided a simple example showing how this is done — check it out liveand look at the source code to see if you can spot the incrementors!How it works.

Math is a built in object in JavaScript that contains certain methods useful for performing mathematical tasks. One of these methods is min. The problem with Math. To illustrate this, take a look at the code below:. As you can see, Math. Because of this, we need to make use of the … spread operator. When we use the spread operator within Math.

## Recursion and stack

In other words: Math. If arrow functions scare you, simply remember that the two functions below are the same:. This function is almost identical to the the Minimum value function explained above.

Please scroll up for a read-through on how this function works. The only difference is this function makes use of the Math. The code above is identical to this function:. No matter how you write it, This function makes use of the JavaScript reduce method to reduce our array to a single value. It does this by applying a function to each element in the array. The function that we pass as the first parameter of the reduce method receives two parameters, a and b. In this code, a is our accumulator.

It will accumulate our sum as our function works. The second parameter of the reduce method is the initial value we wish to use.