JavaScript Control Statements - Chapters 7 & 8

Control Statements in JavaScript

• Transfer of control refers to changing the execution order of statements.
• Four fundamental control statements in JavaScript: sequence, selection, repetition, and named blocks.
• Sequential execution processes statements in the order they are written.
• Selection allows the execution of statements based on conditions using if, if...else, and switch constructs.
• Repetition executes statements repeatedly while a specified condition remains true.

Selection Structures

• if statement: Executes actions if a condition is true; otherwise, skips it (single-selection).
• if...else statement: Conducts different actions based on a true or false condition (double-selection).
• switch statement: Selects among multiple options based on the value of an expression (multiple-selection).
• Each case in a switch statement should end with a break to avoid logical errors, except for the last case.

Syntax of Switch Statement

• General structure is:

  switch (expression) {
    case label:
      // statements
      break;
    ...
    default:
      // statements
  }
  

• Case labels can be grouped to execute the same set of actions.

Conditional Operator

• The conditional operator (?:) replaces simpler if...else statements and takes the form condition ? exprIfTrue : exprIfFalse.

Truthy and Falsy Values

• Non-zero numbers, non-empty strings, and all objects are considered truthy.
• Zero, empty strings, null, and undefined variables are considered falsy.

JavaScript Coding Practices

• Whitespace in scripts is ignored; consistent indentation enhances readability.
• Logic errors occur during the execution, affecting the output without causing a script to stop.
• Initializing variables is crucial to avoid NaN errors.

Useful Validation Methods

• parseFloat(): Converts a string to a floating-point number, ignores invalid characters post-conversion point.
• parseInt(): Parses strings to return integers based on a specified radix; ignores invalid characters and truncates floating-point values.
• isNaN(): Determines if a value is NaN, returning true or false.

Error Handling in JavaScript

• Try...Catch statements manage errors and exceptions effectively.
• A try block must be followed by either a catch or finally block; both can exist.

Designing JavaScript Functions

• Identify user interaction controls on the web, such as form inputs.
• Determine necessary event listeners and their scope within the user interface.
• Implement and structure functions based on identified controls and validation needs.

Best Practices in JavaScript Labs

• Adhere to coding and naming conventions strictly.
• Avoid inline event handlers; prefer using addEventListener for better practice and compliance with standards.
• Document all interactions and validate inputs systematically for robust application design.

This quiz explores Chapters 7 and 8 of 'How to Program, 5/e' focused on JavaScript control statements. Participants will learn essential problem-solving techniques and algorithms, including the use of selection statements and repetition constructs such as while loops. Test your knowledge on how to implement these concepts effectively in programming.