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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

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
Maciej
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Virgil
is Bucky paper clear?
CYNTHIA
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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.
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s.
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SUYASH Reply
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SUYASH
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s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
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Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
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after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
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name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
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how did you get the value of 2000N.What calculations are needed to arrive at it
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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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