Voice of a Developer: Parse JSON - Part 28

• The data is written as name/value pairs, like JavaScript object properties, e.g.,
  1. {“fname”:”sumit”}
• JSON objects are inside curly braces {}, separated by “,”
  1. {“fname”:”sumit”, “lname”:”jolly”}
• Arrays are written inside square brackets
  1. {'students': [
  2. {'name':'Ravi','year':'1st'},
  3. {'name':'Abhishek','year':'1st'},
  4. {'name':'Neha','year':'2nd'}]};

JSON	XML
JSON is less verbose	XML has a lot of baggage and has a lot of opening and closing tags
Easily readable format by humans	Complex to read large XML files
JSON is data-oriented	XML is document-oriented
JSON notation is built in JavaScript	XML needs the extra library to process it
JSON is just a data interchange format	XML is more than interchange format, it’s like a language
No namespace concept, each object is its own namespace. So names can be repeated	XML supports namespaces and prefixes

Syntax text: the string to parse a JSON

reviver (optional)

It is a function to screen or modify values that are being parsed. It is invoked on each data item being parsed, like an iterator. It takes two arguments, like KVP's name and value. You need to address topmost value separately in the reviver call. Example,

Syntax Error

In case there is any error in string or reviver then a syntax error is thrown example- I removed on double-quote from lname value.

JSON.stringify()

It converts a JavaScript value to JSON string. Syntax

• value: The value to convert to a JSON string
• replacer (optional): This second argument is used to screen and modify the results like reviver in JSON.parse. It accepts KVP name-value pair:
• space (optional): We can add number of whitespace characters also,
  1. var numberJson = ['one', 'two', 'three'];
  2. var json = JSON.stringify(numberJson, function(k,v){
  3. if (k === '') { return v; }
  4. console.log(v);
  5. return v.toUpperCase();
  6. }, 4);
  7. console.log(json); // I added 4 characters as whitespace, so below output will be generated

Summary

My take away from this is JSON over XML and parameters are available in parse and stringify methods. Please share your feedback/comments.