reading-notes

Class 8: Operators and Loops

Resources

• Expressions and Operators
• Loops

Some Notes

Assignment Operators

• Assignment: x = f()
• Addition Assignment: x += f()
• Subtraction Assignment: x -= f()
• Multiplication Assignment: x *= f()
• Division Assignment: x /= f()
• Remainder Assignment: x %= f()
• Exponentiation Assignment: x **= f()
• Left Shift Assignment: x «= f()
• Right Shift Assignment: x »= f()
• Unsigned Right Shift Assignment: x »>= f()
• Bitwise AND Assignment: x &= f()
• Bitwise XOR Assignment: x ^= f()

• Bitwise OR Assignment: x

  = f()

• Logical AND Assignment: x &&= f()

• Logical OR Assignment: x

  = f()

• Nullish Coalescing Assignment: x ??= f()

Comparison Operators

• Eqaul: (==)
• Not Eqaul: (!=)
• Strict Equal: (===)
• Strict Not Equal: (!==)
• Greater Than: (>)
• Greater Than or Eqaul: (>=)
• Less Than: (<)
• Less Than or Eqaul: (<=)

For Statements

• A for loop repeats until a specified condition evaluates to false.
  • for ([initialExpression]; [conditionExpression]; [incrementExpression]) statement
• While a for loop executes:
  • 1. [initailExpression] (if any) is executed.
  • 1. [conditionExpression] is evaluated. If the value of [conditionExpression] is true, the loop statements execute. Otherwise, the for loop terminates. If the [conditionExpression] is omitted entirely, the condition is assumed to be true.
  • 1. The statement executes. To execute multiple statements, use a block statement ({}) to group those statements.
  • 1. If present, the [incrementExpression] is executed.
  • 1. Control returns to Step 2.

While Statements

• A while statement executes its statement as long as a specified condition evaluates to true.
  • while (condition) statement
• If the condition becomes false, statement within the loop stops executing and control passes to the statement following the loop.
• The condition test occurs before statement in the loop is executed. If the condition returns true, statement is executed and the condition is tested again. If the condition returns false, execution stops, and control is passed to the statement following while.
• To execute multiple statements, use a block statement ({}) to group those statements.

Example: let n = 0; let x = 0; while (n < 3) { n++; x += n; }

Practice

function favColor(){ let userGuess = prompt(“What is my favorite color?”); if (userGuess == “yellow”){ console.log(“That is correct”); } else { console.log(“That is wrong”); favColor(); } } // This function will continue to loop until the correct answer is given.

Things I Would Like to Know

I would like to get to a point skillwise where I can tell when it’s most efficient to loop with a function, or with an actual loop (whether the loop is a for loop or a while loop).