Javascript “this” keyword

The “this” keyword is an indispensable, yet often mis-understood, concept in JavaScript object-oriented programming. When used in a JavaScript constructor function, “this” refers to the specific instance of the Object. Through the “this” keyword, properties and methods can be assigned object, also known as a class.

For example:

function Square(intSideLength)
{
this.sideLength = intSideLength;
}

In the preceding example the “this” keyword is used to assign the variable “sideLength” as a property of the Square class.
The “this” keyword is also frequently passed as a parameter on JavaScript events, such as when a checkbox is clicked. In such an instance, “this” refers to the current object, the checkbox.

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JSON – JavaScript Object Notation

Here’s another simple way to optimize code and network traffic. XML… by it’s very definition is wasteful as it exchanges size for readability. JSON is a different approach that maintains readability as well as reduces the size to a minimum. This method can be used in any client-server environment, not just between a browser and server.

JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for humans to and machines to read/parse and write/generate. JSON is a text format that is completely language independent but uses conventions that are familiar to most programmers familiar with OO languages.

JSON is built on two structures:

  • A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
  • An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

Key Concepts:

  • An object is an unordered set of name/value pairs. An object begins with { (left brace) and ends with } (right brace). Each name is followed by : (colon) and the name/value pairs are separated by , (comma).
  • An array is an ordered collection of values. An array begins with [ (left bracket) and ends with ] (right bracket). Values are separated by , (comma).
  • A value can be a string in double quotes, or a number, or true or false or null, or an object or an array. These structures can be nested.
  • A string is a collection of zero or more Unicode characters, wrapped in double quotes, using backslash escapes. A character is represented as a single character string. A string is very much like a C or Java string.
  • A number is very much like a C or Java number, except that the octal and hexadecimal formats are not used.

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Cheers!