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JavaScript: Find the length of an object

JavaScript Object: Exercise-3 with Solution

Write a JavaScript program to get the length of a JavaScript object.

Sample object:
var student = {
name : "David Rayy",
sclass : "VI",
rollno : 12 };

Sample Solution: -

HTML Code:

<!DOCTYPE html>
  <html>
  <head>
  <meta charset="utf-8">
  <title>Write a JavaScript program to get the length of a JavaScript object.</title>
  </head>
  <body>
 </body>
  </html>
  

JavaScript Code:

//Write a JavaScript program to get the length of a JavaScript object.

Object.objsize = function(Myobj) {
    var osize = 0, key;
    for (key in Myobj) {
        if (Myobj.hasOwnProperty(key)) osize++;
    }
    return osize;
};

var student = { 
name : "David Rayy", 
sclass : "VI", 
rollno : 12 };

var objsize = Object.objsize(student);
console.log('Size of the current object : '+objsize);

Sample Output:

Size of the current object : 3

Flowchart:

Flowchart: JavaScript - Find the length of an object.

Live Demo:

See the Pen javascript-object-exercise-3 by w3resource (@w3resource) on CodePen.


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Previous: Write a JavaScript program to delete the rollno property from the following object. Also print the object before or after deleting the property.
Next: Write a JavaScript program to display the reading status (i.e. display book name, author name and reading status) of the following books.

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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