JavaScript Numbers & Math
Mathis a built-in object holding mathematical constants and functions.
You never create a Math object; everything on it is static.
Call the methods directly on Math.
Example
javascript
console.log(Math.abs(-5));
console.log(Math.sqrt(16));
console.log(Math.PI);The output is 5, 4, then pi.
Constants such as Math.PI and Math.E.
Functions such as abs, sqrt, pow and sign.
Rounding and random, which have their own lessons.
Syntax
javascript
Math.abs(value);
Math.sqrt(value);Math is never used with new.
abs removes the sign, which is useful for differences.
Example
javascript
console.log(Math.abs(-5));
console.log(Math.abs(5));
console.log(Math.abs(3 - 8));The last one is the distance between two numbers.
pow and the ** operator do the same job.
Example
javascript
console.log(Math.pow(2, 10));
console.log(2 ** 10);
console.log(Math.sqrt(144));
console.log(Math.cbrt(27));** is the modern way to write a power.
sign returns -1, 0 or 1.
Example
javascript
console.log(Math.sign(-42));
console.log(Math.sign(0));
console.log(Math.sign(42));Useful for deciding a direction.
Math.PI is the one you will actually use.
Example
javascript
const radius = 3;
console.log(Math.PI > 3.14 && Math.PI < 3.15);
console.log(Math.round(Math.PI * radius * radius));The area of the circle, rounded, is 28.
Trying to create a Math object throws an error.
Example
javascript
let message;
try {
new Math();
} catch (error) {
message = "Math is not a constructor";
}
console.log(message);It is a collection of tools, not a type of thing.
Complete Example
html
<!DOCTYPE html>
<html>
<head>
<title>JavaScript Math Object</title>
</head>
<body>
<h1>The Math Object</h1>
<p id="out"></p>
<script>
const radius = 5;
document.getElementById("out").innerHTML =
"Circle area: " + (Math.PI * radius * radius).toFixed(2) +
"<br>Square root of 144: " + Math.sqrt(144) +
"<br>2 to the power 10: " + Math.pow(2, 10) +
"<br>Distance between 3 and 8: " + Math.abs(3 - 8);
</script>
</body>
</html>Run the above example in the Try It Editor.
Try a bigger circle:
Change the radius and watch the area change.
Math is a built-in object of static tools.Math.abs removes the sign.Math.sqrt and Math.pow handle roots and powers.Math.PI is the circle constant.Math is never used with new.Math collects the calculations that are not operators.
You will meet abs, sqrt and PI most often.
Rounding and random are common enough to deserve their own lessons.