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The variable named jSonStr01 is (or contains) a JSON string.

The only difference between the two is the pair of single quotes that surrounds the expression on the right side of the assignment operator for jSonStr01 .

The keys in the JavaScript object are surrounded by double quotes. This is optional. If those quotes were removed, the JavaScript object wouldstill be a JavaScript object.

Output from the script

After creating the JavaScript object and the JSON string, the code in Listing 14 executes four write statements to display information about the object and the string. Theresults are shown in Figure 6 .

Figure 6 . Output from the script.
1. John 2. undefined3. [object Object] 4. {"name":"Bill","age":33}

Without getting into the details, the output in Figure 6 confirms that jScrObj01 contains a JavaScript object and jSonStr01 contains a JSON string.

Transform them both

The code in Listing 15

  • calls the JSON.parse method to transform the JSON string into a JavaScript object, and
  • calls the JSON.stringify method to transform the JavaScript object into a JSON string.
Listing 15 . Transform them both.
var jScrObj02 = JSON.parse(jSonStr01); var jSonStr02 = JSON.stringify(jScrObj01);document.write("<br/>5. " + jScrObj02.name); document.write("<br/>6. " + jSonStr02.name);document.write("<br/>7. " + jScrObj02); document.write("<br/>8. " + jSonStr02);</script></body>

Output from the script

After that, the code in Listing 15 executes four write statements to display information about the new object and the new string. Theresults are shown in Figure 7 .

Figure 7 . Output from the script.
5. Bill 6. undefined7. [object Object] 8. {"name":"John","age":33}

Once again, without getting into the details, the output in Figure 7 confirms that jScrObj02 is a JavaScript object and jSonStr02 is a JSON string.

Run the scripts

I encourage you to copy the code from Listing 16 , Listing 17 , Listing 18 , and Listing 13 . Load the code into your favorite browser and observe the output. Experiment with the code, making changes, and observing the results of your changes. Make certain that youcan explain why your changes behave as they do.

Debugging JavaScript

Finding and correcting errors in your JavaScript code can be difficult. Sometimes when your JavaScript isn't working properly, opening the Firefox WebConsole will provide useful diagnostic information about the error.

To open the Web Console in Firefox version 26,

  • Select Tools
  • Hover on Web Developer
  • Select Web Console

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Json0130: JSON and JavaScript
  • File: Json0130.htm
  • Published: 02/02/14
  • Revised: 02/08/16
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

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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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