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Javascript

What is JavaScript?

  • Javascript is a language used to create dynamic content for websites
  • HTML adds structure to a web page, CSS styles it, and Javascript brings it to life by allowing users to interact with elements on the page.
  • Javascript is also used on the server side to access databases, file handling and security features to send responses to browsers.

What can Javascript do?

  • JS gives HTML designers a programming tool.
  • JS can put dynamic texts into an HTML page.
  • JS can read and write HTML elememts.

JAVASCRIPT VARIABLES.

  • Variables are 'containers' for storing information.
  • Js variables are used to hold values or expressions.
  • A variable can have a short name, like x, or a more descriptive name like carname.
  • Rules for Javascript variable names;
    1. Variable names are case sensitive(y and Y are two different variables).
    2. Variable names must begin with a letter or the underscore character.

Declaring Javascript variables.

  • You can declare javascript variable with the var statement; Var x; var carname;
  • You can also assign values to the variables when you declare them: var x = 5; var carname = "Scorpio"

Data types

  1. Numbers - Are values that can be processed and calculated. You don't enclose them in quotation marks and can either be - or +.
  2. Strings - Are a series of letters or numbers enclosed in quotation marks. e.g "greetings" or "fun".
  3. Boolean (true or false) - Let's you evaluate whether a condition meets or doesn't meet the specified criteria.
  4. Null - It is an empty value. Null is not the same as 0 -- 0 is a real, calculable number, whereas null is the abscence of any value.

Javascript operators.

  • The operator = is used to assign values.
  • The operator + is used to add values together.
  • The operator - is used to subtract values.

JavaScript comparison and logical operators.

Comparison operators.

  • Are used in logical statements to determine equality or differece between values or variables.
  • Given that x=5, the table explains the comparison operators. | Operator | Description | Examples | |:----------|:---------------------:|----------:| | == | is equal to | x==8 is false | | === | is exactly equal to(value & type) | x===5 is true | | != | is not equal | x!= 8 is true |
  • How can it be used:
  • Can be used in conditional statements to compare values and take action depending on the results

Logical operators.

  • Are used to determine the logic between values or variables.

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