# JavaScript: Calculate the volume of a Cylinder

## JavaScript Object: Exercise-5 with Solution

Write a JavaScript program to get the volume of a Cylinder with four decimal places using object classes.
Volume of a cylinder : V = πr2h
where r is the radius and h is the height of the cylinder.

Sample Solution: -

HTML Code:

``````<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>Volume of a Cylinder</title>
<body>
</body>
</html>
```
```

JavaScript Code:

``````function Cylinder(cyl_height, cyl_diameter) {
this.cyl_height = cyl_height;
this.cyl_diameter = cyl_diameter;
}

Cylinder.prototype.Volume = function () {
var radius = this.cyl_diameter / 2;
};

var cyl = new Cylinder(7, 4);
// Volume of the cylinder with four decimal places.
console.log('volume =', cyl.Volume().toFixed(4));
```
```

Sample Output:

```volume = 87.9646
```

Flowchart:

Live Demo:

See the Pen javascript-object-exercise-5 by w3resource (@w3resource) on CodePen.

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## JavaScript: Tips of the Day

instance

```class Calc {
constructor() {
this.count = 0
}

increase() {
this.count ++
}
}

const calc = new Calc()
new Calc().increase()

console.log(calc.count)
```

We set the variable calc equal to a new instance of the Calc class. Then, we instantiate a new instance of Calc, and invoke the increase method on this instance. Since the count property is within the constructor of the Calc class, the count property is not shared on the prototype of Calc. This means that the value of count has not been updated for the instance calc points to, count is still 0.

Ref: https://bit.ly/2Hcpkm6