Web Front-endJS TutorialHow to create a dynamic length array with numbers and sum the numbers using JavaScript?How to create a dynamic length array with numbers and sum the numbers using JavaScript?
In JavaScript, the length of an array is always dynamic. Like other programming languages, we do not need to define the length of the array when creating it. So, we can create an array and push any number of elements into the JavaScript array. Here we will create a dynamic length of the array and add numbers to it. After that, we will sum all the numbers. This tutorial will teach us to create a dynamic length array containing numbers and sum the numbers using JavaScript.
Use a for loop to sum all elements of a dynamic array
We can use a for loop to iterate over the array and add each element to get the sum of all elements. We will use a normal for loop and a for-of loop to access the array elements and add all elements into a single variable.
grammar
Users can use the for loop to sum all elements of a dynamic length array according to the following syntax.
let arraySum = 0;
for (let i = 0; i < length; i++) {
arraySum += dynamicArray[i];
}
In the above syntax, length is the length of the dynamic array. We add all elements to the arraySum variable.
step
Use the Math.random() method and generate a random integer to use as the length of the dynamic array.
In addition, the length range of a dynamic array can be defined by multiplying a randomly generated length by any integer. For example, if you want to create a dynamic array with a length between 0 and 15, multiply the random integer by 15 because it will generate a value between 0 and 10.
Now, use a for loop to initialize the values. To initialize the random value, we again use the Math.random() method and multiply it by 5 to generate a random value between 0 and 5.
Use the Math.round() method to round randomly generated numbers.
Create an arraysum variable and initialize it with zeros.
Now, iterate over each element of the array and arraySum variable.
Example 1
In the following example, we use the Math.random() function to generate the length of a dynamic array, initialize the array with random values, and use for-lop to sum all array values.
In the output, the user can see the values of the array and their sum. Additionally, every time the user runs the code below, it creates a new array with different lengths and values.
<html>
<body>
<h2 id="Using-the-i-for-loop-i-add-all-elements-of-the-array-of-numbers-of-dynamic-length">Using the <i> for-loop </i> add all elements of the array of numbers of dynamic length.</h2>
<div id = "output"> </div>
<script>
let output = document.getElementById('output');
let length = Math.random() * 15;
let dynamicArray = [];
for (let i = 0; i < length; i++) {
dynamicArray[i] = Math.round(Math.random() * 5);
}
let arraySum = 0;
for (let i = 0; i < length; i++) {
arraySum += dynamicArray[i];
}
output.innerHTML += "The array of random number is " + dynamicArray + "<br/>";
output.innerHTML += "The sum of all array elements is " + arraySum + "<br/>";
</script>
</body>
</html>
Example 2
In the example below, we get the length of a dynamic array from the user. Additionally, we get each value of the array from the user. After storing the user input into a dynamic array, we iterate over it using a for-of loop.
As the for loop iterates, we add each element of the array to the sum variable.
<html>
<body>
<h2 id="Using-the-i-for-of-loop-i-add-all-elements-of-the-array-of-numbers-of-dynamic-length">Using the <i> for-of loop </i> add all elements of the array of numbers of dynamic length.</h2>
<div id = "output"> </div>
<script>
let output = document.getElementById('output');
// take the dynamic length of the array from users
let length = +prompt("Enter a length of the dynamic array", 5);
let dynamicArray = [];
// take array inputs from users
for (let i = 1; i <= length; i++) {
dynamicArray.push(+prompt("Enter " + i + "th number value", 0))
}
let sum = 0;
// using the for-of loop to get a sum of all elements
for (let element of dynamicArray) {
sum += element;
}
output.innerHTML += "The array of random number is " + dynamicArray + "<br/>";
output.innerHTML += "The sum of all array elements is " + sum + "<br/>";
</script>
</body>
</html>
Use the array.reduce() method to sum all numbers in a dynamic array
The array.reduce() method reduces an array to a single element by performing multiple operations. We can create a variable to store the sum of all array elements and reduce the array by adding each element to the sum variable.
grammar
Users can use the reduce() method to sum all elements of a dynamic array according to the following syntax
let sumOfArray = inputArray.reduce((element, currentSum) => element + currentSum, 0)
In the above syntax, element is the element of the array, currentSum is the sum of all elements of the array up to the i-th index, and the sum of the array contains the final sum of all array elements.
Example 3
In the example below, we create a dynamic array by getting user input. Additionally, the user can also notice that we used the " " unary operator before the prompt to convert the string to a number.
Finally, we use the array.reduce() method to sum all user input stored in the array.
Using the array.reduce() method to add all elements of the array of numbers of dynamic length
<script> let output = document.getElementById('output'); let arrayLen = +prompt("Enter any number to create array of that length", 10); let inputArray = []; for (let i = 1; i <= arrayLen; i++) { inputArray[i] = +prompt("Enter " + i + "th number value", 5); } let sumOfArray = inputArray.reduce((element, currentSum) => element + currentSum, 0) output.innerHTML += "The length of the array is " + arrayLen + "<br/>"; output.innerHTML += "The array of random number is " + inputArray + "<br/>"; output.innerHTML += "The sum of all array elements is " + sumOfArray + "<br/>"; </script>
We learned how to create dynamic length arrays in JavaScript. Additionally, we learned to use a for loop and the reduce() method to sum all elements of a dynamic length array. We can also use while loop.
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