Knowledge Walls
John Peter
Pune, Maharashtra, India
Examples
How to generate random colors in javascript with Example How to use call by reference in Javascript functions with Example How to use call by value in Javascript functions with Example How to clone or copy Object in Javascript with Example How to convert javascript object to JSON string using javascript with Example How to convert JSON string to Javascript Object in Javascript with Example How to use foreach loop in javascript with Example
Examples [cont'd]
How to use nested for loop in javascript with Example How to use switch case statement in javascript with Example How to use onclick method in javascript with Example How to use setInterval and clearInterval methods in javascript with Example How to get first key of json object in javascript with Example. How to push and pop method in javascript array object with Example Difference between innerHTML and outerHTML in Javascript Element Object with Example
Examples [cont'd]
How to use focus() and blur() method in Javascript with Example How to read client side local file in javascript using FileReader Class with Example How to load image from client machine to browser using Javascript with Example Base64 encode and decode using btoa() and atob() methods in javascript with example How to get current web page url, hostname, port, protocol And URI in Javascript How to call javascript function on enter keypress in textbox with Example How to use getElementsByName method in Javascript with Example
Examples [cont'd]
How to use css styles using javascript with Example How to validate textbox using javascript with Example How to validate checkbox using Javascript and HTML with Example How to validate radio box using Javascript and HTML with Example How to validate textarea using Javascript and HTML with Example How to validate combobox using Javascript and HTML with Example How to validate multiselect combobox in Javascript and HTML with Example
Examples [cont'd]
How to create multiselect combobox with checkbox in Javascript and HTML with Example How to join arrays in Javascript with Example
How to get first key of json object in javascript with Example.
42468 Views
Hints 
for loop runs one time to get first key.

Thus,
for(var firstKey in data);

Using firstKey taking the from data object. Thus data[firstKey] returns the first value from an array object.
FirstKey and firstValue of the JSON
var data = {};
    data.rno = 1001;

for(firstKey in data);

document.write(firstKey+"<br />");
document.write(data[firstKey]+"<br />");
Demo & Output 
[Click here to see Demo]
Best Lessons of "Good Javascript Examples"
Top lessons which are viewed more times.
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
Examples of Good Javascript Examples
  Copyright © 2014 Knowledge walls, All rights reserved
KnowledgeWalls
keep your tutorials and learnings with KnowledgeWalls. Don't lose your learnings hereafter. Save and revise it whenever required.
Click here for more details