JavaScript Object - Exercises, Practice, Solution
JavaScript Object [18 exercises with solution]
[An editor is available at the bottom of the page to write and execute the scripts.]
1. Write a JavaScript program to list the properties of a JavaScript object. Go to the editor
Sample object:
var student = {
name : "David Rayy",
sclass : "VI",
rollno : 12 };
Sample Output: name,sclass,rollno
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2. Write a JavaScript program to delete the rollno property from the following object. Also print the object before or after deleting the property. Go to the editor
Sample object:
var student = {
name : "David Rayy",
sclass : "VI",
rollno : 12 };
Click me to see the solution
3. Write a JavaScript program to get the length of a JavaScript object. Go to the editor
Sample object :
var student = {
name : "David Rayy",
sclass : "VI",
rollno : 12 };
Click me to see the solution
4. Write a JavaScript program to display the reading status (i.e. display book name, author name and reading status) of the following books. Go to the editor
var library = [ { author: 'Bill Gates', title: 'The Road Ahead', readingStatus: true }, { author: 'Steve Jobs', title: 'Walter Isaacson', readingStatus: true }, { author: 'Suzanne Collins', title: 'Mockingjay: The Final Book of The Hunger Games', readingStatus: false }];
5. Write a JavaScript program to get the volume of a Cylinder with four decimal places using object classes. Go to the editor
Volume of a cylinder : V = πr2h
where r is the radius and h is the height of the cylinder.
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6. Write a Bubble Sort algorithm in JavaScript. Go to the editor
Note : Bubble sort is a simple sorting algorithm that works by repeatedly stepping through the list to be sorted,
Sample Data: [6,4,0, 3,-2,1]
Expected Output : [-2, 0, 1, 3, 4, 6]
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7. Write a JavaScript program which returns a subset of a string. Go to the editor
Sample Data: dog
Expected Output: ["d", "do", "dog", "o", "og", "g"]
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8. Write a JavaScript program to create a Clock. Go to the editor
Note: The output will come every second.
Expected Console Output :
"14:37:42"
"14:37:43"
"14:37:44"
"14:37:45"
"14:37:46"
"14:37:47"
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9. Write a JavaScript program to calculate the area and perimeter of a circle. Go to the editor
Note : Create two methods to calculate the area and perimeter. The radius of the circle will be supplied by the user.
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10. Write a JavaScript program to sort an array of JavaScript objects. Go to the editor
Sample Object :
var library = [ { title: 'The Road Ahead', author: 'Bill Gates', libraryID: 1254 }, { title: 'Walter Isaacson', author: 'Steve Jobs', libraryID: 4264 }, { title: 'Mockingjay: The Final Book of The Hunger Games', author: 'Suzanne Collins', libraryID: 3245 }];
Expected Output:
[[object Object] { author: "Walter Isaacson", libraryID: 4264, title: "Steve Jobs" }, [object Object] { author: "Suzanne Collins", libraryID: 3245, title: "Mockingjay: The Final Book of The Hunger Games" }, [object Object] { author: "The Road Ahead", libraryID: 1254, title: "Bill Gates" }]
11. Write a JavaScript function to print all the methods in an JavaScript object. Go to the editor
Test Data :
console.log(all_properties(Array));
["length", "name", "arguments", "caller", "prototype", "isArray", "observe", "unobserve"]
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12. Write a JavaScript function to parse an URL. Go to the editor
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13. Write a JavaScript function to retrieve all the names of object's own and inherited properties. Go to the editor
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14. Write a JavaScript function to retrieve all the values of an object's properties. Go to the editor
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15. Write a JavaScript function to convert an object into a list of `[key, value]` pairs. Go to the editor
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16. Write a JavaScript function to get a copy of the object where the keys have become the values and the values the keys. Go to the editor
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17. Write a JavaScript function to check whether an object contains given property. Go to the editor
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18. Write a JavaScript function to check whether a given value is a DOM element. Go to the editor
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More to Come !
* To run the code mouse over on Result panel and click on 'RERUN' button.*
Live Demo:
See the Pen javascript-common-editor by w3resource (@w3resource) on CodePen.
Do not submit any solution of the above exercises at here, if you want to contribute go to the appropriate exercise page.
JavaScript: Tips of the Day
How to insert an item into an array at a specific index (JavaScript)?
What you want is the splice function on the native array object.
arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:
var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());
Ref: https://bit.ly/2BXbp04
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