JavaScript Loops & Functions

Topic 15: Logical Operators

Logical operators combine or manipulate boolean values (true/false)

Operator	Name	Description	Example
&&	AND	Returns true if BOTH conditions are true	`true && true = true`
\|\|	OR	Returns true if AT LEAST ONE condition is true	`true \|\| false = true`
!	NOT	Reverses the boolean value	`!true = false`

Example 1 (AND): Temperature check - weather is good if temp > 0 AND temp <= 30
Example 2 (OR): Temperature check - weather is bad if temp <= 0 OR temp > 30
Example 3 (NOT): Sunny check - if NOT sunny, it's cloudy

Different ways to compare values in JavaScript

Operator	Name	Description	Example
=	Assignment	Assigns a value to a variable	`x = 5`
==	Equality	Compares values (ignores datatype)	`5 == "5" - true`
===	Strict Equality	Compares values AND datatype	`5 === "5" - false`
!=	Inequality	Checks if values are NOT equal	`5 != 3 - true`
!==	Strict Inequality	Checks if values OR datatype are NOT equal	`5 !== "5" - true`

Best Practice: Always use === and !== to avoid unexpected behavior!

Comparing PI (number) with "3.14" (string) using strict equality (===)

While loops repeat code WHILE a condition is true


          while(condition){

            // code to repeat

          }

Do-While Loop: Executes code at least once, then checks condition

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When to use: When you don't know how many times to repeat (e.g., waiting for valid input)

For loops repeat code a LIMITED number of times


          for(initialization; condition; increment){

            // code to repeat

          }

initialization: Starting value (let i = 1)
condition: Continue while true (i <= 10)
increment: Change after each loop (i++)

For vs While:
For loop: When you know how many times to repeat
While loop: When you don't know how many times to repeat

Functions are reusable blocks of code


          function functionName(parameter1, parameter2){

            // code to execute

            return value; // optional

          }

Why use functions?