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Math Object

4 min read

When diving into JavaScript, you’ll quickly discover that performing mathematical operations is a common task. While basic arithmetic operators can handle simple calculations, JavaScript offers a built-in Math object to tackle more complex math challenges.

This handy tool provides a variety of methods that make it easier to perform advanced calculations and manipulate numbers. Let’s explore these methods and see how they can simplify your coding experience.

The Math.random() method generates a random floating-point number between 0 (inclusive) and 1 (exclusive). This means the possible output can be 0, but it will never actually reach 1. Here is an example working with the Math.random() method:

const randomNum = Math.random();
 
console.log(randomNum); 
// any number between 0 and 1 – 0 inclusive and 1 exclusive

Math.min() and Math.max() both take a set of numbers and return the minimum and maximum value, respectively. Here is an example of working both of those methods:

const smallest = Math.min(1, 5, 3, 9);
console.log(smallest); // 1
 
const largest = Math.max(1, 5, 3, 9);
console.log(largest); // 9

The first console.log() will log the number 1, since 1 is the smallest in that list of numbers. And the second console.log() will log the number 9, since 9 is the largest numbers in that list.

If you wanted to round numbers up or down to the nearest whole integer, you could use the Math.ceil() and Math.floor() methods. Here is an example of working with Math.ceil():

console.log(Math.ceil(4.3)); // 5

Math.ceil() will round 4.3 up to the nearest whole integer, which is 5 in this case. Now, let’s take a look at rounding a number down:

console.log(Math.floor(4.7)); // 4

Math.floor() will round 4.7 down to the nearest whole integer, which is 4 in this case. Math.round() is the hybrid of Math.ceil() and Math.floor(). It rounds a number to its nearest integer, taking the decimal point into account:

console.log(Math.round(2.3)); // 2
console.log(Math.round(4.5)); // 5
console.log(Math.round(4.8)); // 5

So, if the decimal point is less than 5, the number is rounded down. And if the decimal point is 5 or greater, the number is rounded up. A practical application of Math.floor() and Math.random() is to generate a random number between two whole numbers. Here’s the syntax for that:

Math.floor(Math.random() * (max - min)) + min;

Generating a random number between 20 and 1 would look like this:

const randomNumBtw1And20 = Math.floor(Math.random() * 20) + 1;
console.log(randomNumBtw1And20);

Another helpful Math method would be the Math.trunc() method. Math.trunc() removes the decimal part of a number, returning only the integer portion, without rounding:

console.log(Math.trunc(2.9)); // 2
console.log(Math.trunc(9.1)); // 9

If you need to get the square root or cube root of a number, you can use the Math.sqrt() and Math.cbrt() methods, respectively:

console.log(Math.sqrt(81)); // 9
console.log(Math.cbrt(27)); // 3

The first log statement, will log 9 because the square root of 81 is 9, while the second log statement will log 3 because the cube root of 27 is 3. If you need to get the absolute value of a number, you can use the Math.abs() method:

console.log(Math.abs(-5)); // 5
console.log(Math.abs(5)); // 5

Math.abs() returns the absolute value of a number, turning negatives into positives. The last method we will look at will be the Math.pow() method:

console.log(Math.pow(2, 3)); // 8
console.log(Math.pow(8, 2)); // 64

Math.pow() takes two numbers and raise the first to the power of the second. There are many more methods that belong to the Math object, that you can explore on your own. However, these are just a few of the more commonly used ones found in JavaScript codebases.

Number constants

Here are some of the built-in number constants that exist on the Math object:

  • The PI number: Math.PI which is approximately 3.14159

  • Euler’s number: Math.E which is approximately 2.718

  • The natural logarithm of 2: Math.LN2 which is approximately 0.693

Rounding methods

These include:

  •  Math.ceil() - rounds up to the closest integer

  •  Math.floor() - rounds down to the closest integer

  •  Math.round() - rounds up to the closest integer if the decimal is .5 or above; otherwise, rounds down to the closest integer

  •  Math.trunc() - trims the decimal, leaving only the integer

Arithmetic and calculus methods

Here is a non-conclusive list of some common arithmetic and calculus methods that exist on the Math object:

  • Math.pow(2,3) - calculates the number 2 to the power of 3, the result is 8 

  • Math.sqrt(16) - calculates the square root of 16, the result is 4 

  • Math.cbrt(8) - finds the cube root of 8, the result is 2 

  • Math.abs(-10) - returns the absolute value, the result is 10 

  • Logarithmic methods: Math.log(), Math.log2(), Math.log10() 

  • Return the minimum and maximum values of all the inputs: Math.min(9,8,7) returns 7, Math.max(9,8,7) returns 9.

  • Trigonometric methods: Math.sin(), Math.cos(), Math.tan(), etc.

Logarithmic Methods

Math.log(x) - Returns the natural logarithm (base e) of x.

Math.log2(x) - Returns the base-2 logarithm of x.

Math.log10(x) - Returns the base-10 logarithm of x.

Logarithmic Methods

Math.log(x) - Returns the natural logarithm (base e) of x.

Math.log2(x) - Returns the base-2 logarithm of x.

Math.log10(x) - Returns the base-10 logarithm of x.

Conclusion

You can assign the results of JavaScript’s Math functions to variables to store and reuse calculated values.

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var MyNum = Math.sqrt(16); // Calculates square root of 16
 
console.log(MyNum); // Output: 4
 
//This approach works for any Math function:
 
var MyNum = Math.pow(3, 4) will assign the value 81 to MyNum.

It is done to simplify the calculations, make your code cleaner, or use the results later.

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