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Learn how to write and call external JavaScript functions when working with JSON strings.

Table of contents


This module is one in a collection of modules designed for teaching ITSE 1356 Introduction to XML at Austin Community College in Austin, TX.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand the Listings while you are reading about them.



  • Listing 1 . Beginning of the file named Asg.htm.
  • Listing 2 . Call a function named objToStr.
  • Listing 3 . Call a function named strToObj.
  • Listing 4 . The HTML file named Asg.htm.
  • Listing 5 . The JavaScript file named Asg.js.


Previous modules in this collection have shown you how to transform JavaScript objects into JSON strings, and how to transform JSON strings intoJavaScript objects. Those program placed all of the JavaScript code in an HTML file. Sometimes you will need to break some of the JavaScript code outinto a separate file. You will learn how to do that in this module.

Discussion and sample code

This module will show you how to create an HTML file ( Asg.htm ) and a separate JavaScript file ( Asg.js ) containing functions that are called by JavaScript code in the HTML file. The JavaScript file will contain two functions:

  • A function named objToStr receives a JavaScript object as an incoming parameter and returns a JSON string that represents theobject.
  • A function named strToObj receives a JSON string as an incoming parameter and returns a JavaScript object that represents the string.

A complete listing of the HTML file is provided in Listing 4 near the end of the lesson. A complete listing of the JavaScript file is provided in Listing 5 near the end of the lesson.

Program output

Figure 1 shows the text that appears in a browser window when the files named Asg.htm and Asg.js are stored in the same folder and the file named Asg.htm is opened in a browser. Keep this figure handy so that you can refer to it while viewingthe code.

Figure 1 . Program output.
Display keys in object: name age Display values in object: Bill, 31Transform JavaScript object into a JSON string. In objToStrDisplay JSON string {"name":"Bill","age":31} Transform the JSON string into a JavaScript object.In strToObj Display values in object: Bill, 31Display keys in object: name age

Will explain in fragments

As is often the case, I will explain this program in fragments. The beginning of the file named Asg.htm is shown in Listing 1 .

Listing 1 . Beginning of the file named Asg.htm.
<!DOCTYPE html><html><head><title>ITSE 1356</title><script type='text/javascript' src='Asg.js'></script></head><body><script>var obj01 = {name:"Bill",age:31}; document.write("<br/>Display keys in object: "); for (var key in obj01) {if (obj01.hasOwnProperty(key)) { document.write(key + " ");}//end if }//end for loopdocument.write("<br/>Display values in object: "); document.write(obj01.name + ", " + obj01.age);

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introduction to xml. OpenStax CNX. Dec 02, 2014 Download for free at https://legacy.cnx.org/content/col11207/1.18
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