How To Find Minimum And Maximum Value In An Array Using JavaScript

In this challenge you are going to learn how you can get the maximum and the minimum value of an array using JavaScript. First of all we need an array.

What is an Array?

In JavaScript, an array is an ordered list of values. Each value is called an element specified by an index as shown below.

So below we will create an array with JavaScript:

1const numbers = [4, 12, 7, 2, 15]

Result:

Now that we have created our array, we need to create two variables for the: 1. Maximum number 2. Minimum number

Minimum Value

Let's take the minimum variable, first we need to set a value for this variable, it cannot be 0.

But why?

As in our array example, all the values are greater than zero including our actual minimum value. Therefore the minimum value of our array will not be correct, it will just print a value of zero when in fact the minimum number inside this array is actually 2!

How do we overcome this?

We set the minimum value to Infinity.

1let minimum = Infinity

Infinity is a value in JavaScript representing mathematical infinity (∞). It is a number greater than any assignable quantity or countable number. In our case we are using it for comparison since if you compare any value to ∞, the ∞ will always be higher than that number.

Maximum Value

In the case of the maximum value, we will set it to minus Infinity (-∞) because no number is less than -∞.

1let maximum = -Infinity

JavaScript's Built-in Function

With coding there is often many solutions to a problem. Didn't like the last solution? Well here's another using Javascript's built-in functions Math.min and Math.max:

1const numbers = [4, 12, 7, 2, 15];
2
3function getMaxOfArray(numArray) {
4  return Math.max.apply(null, numArray);
5}
6
7function getMinOfArray(numArray) {
8  return Math.min.apply(null, numArray);
9}
10
11console.log( `Maximum Value: ${getMaxOfArray(numbers)}` + `\nMinimum Value: ${getMinOfArray(numbers)}`);

What are Functions?

Functions are blocks of code designed to perform a particular task. Once we have defined a function it can be used many times.

1function name(parameter) {
2  // code to be executed
3};

In this case we create two functions with the names getMaxOfArray and getMinOfArray with the parameter numArray.

Console output

When we call the functions we created, and pass out numbers array through notice that we get the exact same output as before:

One Pager Cheat Sheet

• You can find the maximum and minimum value of an array using JavaScript by creating it and accessing its elements.
• The index of the array determines its minimum value, which in this case is 2, the smallest number of the entire array.
• We set the minimum variable to Infinity and the maximum variable to -Infinity to compare values correctly.
• Yes, Infinity is greater than 5,000,000 because it is an unbounded number that is higher than any assignable quantity.
• Using a For Loop, a comparison of the values inside the array is conducted to find the maximum and minimum values and output them to the console.
• Utilizing Javascript's built-in functions, Math.min and Math.max, we can create our own functions to find the minimum and maximum of an array.
• The for loop iterates through the array and stores the largest and smallest numbers in the maximum and minimum variables which are outputted as "Max Value: 60" and "Min Value: 2".
• The code uses a for loop to compare each number in the array and updates the values of minimum and maximum according to the result, then uses getMaxOfArray and getMinOfArray functions to return the maximum and minimum values.