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

Table of contents

Preface

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.

Figures

Listings

  • 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.

Preview

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

what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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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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