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JavaScript Selection Statements - CP1-6
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JavaScript Selection Statements - CP1-6

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@StreamlinedRainbow

Questions and Answers

What is the primary function of selection statements in JavaScript?

  • To loop through a series of statements.
  • To make decisions based on conditions. (correct)
  • To store variable values.
  • To define function parameters.

    • What does an if-else statement do when its condition evaluates to false?

  • It executes the if block.
  • It executes the else block. (correct)
  • It skips to the end of the code.
  • It throws an error.

    • When would you use an else if statement in JavaScript?

  • To change values in an array.
  • To check multiple conditions successively. (correct)
  • To declare a function.
  • To create an infinite loop.

    • In a switch statement, what is the purpose of the break keyword?

    <p>To prevent fall-through behavior.</p> Signup and view all the answers

    What is the output when the score is set to 50 in the provided if-else example?

    <p>You failed.</p> Signup and view all the answers

    What will the following code output if day is set to 4? switch (day) { case 1: console.log('Monday'); break; case 2: console.log('Tuesday'); break; case 3: console.log('Wednesday'); break; default: console.log('Invalid day'); }

    <p>Invalid day</p> Signup and view all the answers

    Which of the following statements correctly describes a condition in the context of an if statement?

    <p>An expression that evaluates to true or false.</p> Signup and view all the answers

    Which selection statement is most appropriate for evaluating an expression against multiple possible cases?

    <p>switch statement</p> Signup and view all the answers

    What will be the output if the role is set to 'editor'?

    <p>Access to edit content.</p> Signup and view all the answers

    Which statement accurately describes a 'for' loop in JavaScript?

    <p>It runs only when the number of iterations is predetermined.</p> Signup and view all the answers

    What is the correct syntax structure for a 'for' loop?

    <p>for (initialization; condition; increment/decrement) {}</p> Signup and view all the answers

    When would a switch statement default case execute?

    <p>When the role matches no predefined cases.</p> Signup and view all the answers

    What type of tasks are looping statements particularly beneficial for in JavaScript?

    <p>Tasks that are repetitive or require iteration.</p> Signup and view all the answers

    What happens if no conditions are met in an if...else if statement?

    <p>The else block runs, if present.</p> Signup and view all the answers

    What is the purpose of the nested if statement?

    <p>To check secondary conditions only if the primary condition is true.</p> Signup and view all the answers

    In the grading system example, which grade corresponds to marks below 60?

    <p>Grade: F</p> Signup and view all the answers

    Which part of the if statement runs when the condition evaluates to false?

    <p>Code block inside the else.</p> Signup and view all the answers

    What is indicated by the condition within an if statement?

    <p>An expression that can either be true or false.</p> Signup and view all the answers

    When is an else if block executed in an if...else if statement?

    <p>When all previous conditions are false.</p> Signup and view all the answers

    What will the following code output if number is set to 5? if (number % 2 === 0) { console.log('The number is even.'); } else { console.log('The number is odd.'); }

    <p>'The number is odd.'</p> Signup and view all the answers

    In an if...else structure, what is the code block for if responsible for?

    <p>Running code only if the condition is true.</p> Signup and view all the answers

    What is the purpose of the outer condition in a nested if statement?

    <p>To evaluate first before executing any inner conditions</p> Signup and view all the answers

    What will be displayed in the console if the age is 17 and hasMembership is true?

    <p>Access denied. You must be at least 18 years old.</p> Signup and view all the answers

    What does the 'break' statement do in a switch statement?

    <p>It ends the current case block and prevents fall-through</p> Signup and view all the answers

    What happens if no cases match in a switch statement?

    <p>The default block is executed</p> Signup and view all the answers

    Which of the following is NOT a part of the switch statement syntax?

    <p>return</p> Signup and view all the answers

    What will the console output if age is 25 and hasMembership is false?

    <p>Access granted to the general area.</p> Signup and view all the answers

    Which statement best describes nested if statements?

    <p>They allow for a hierarchical structure of conditions</p> Signup and view all the answers

    What is a consequence of omitting the 'break' statement in a switch case?

    <p>It will cause the next case to execute</p> Signup and view all the answers

    Study Notes

    JavaScript Selection Statements

    • Selection statements allow decision-making in programs by executing specific code blocks based on evaluated conditions.
    • Common selection statements include if, else if, else, and switch.

    If-Else Statement

    • Executes a block of code if a condition is true; otherwise, executes the else block.
    • Example: 
      let age = 20;
if (age >= 18) {
    console.log("You are an adult.");
} else {
    console.log("You are a minor.");
}

    Else If Statement

    • Checks multiple conditions in sequence.
    • Example: 
      let score = 85;
if (score >= 90) {
    console.log("Grade: A");
} else if (score >= 75) {
    console.log("Grade: B");
} else {
    console.log("Grade: C");
}

    Switch Statement

    • Evaluates an expression and executes code corresponding to matching cases.
    • Example: 
      let day = 2;
switch (day) {
    case 1:
        console.log("Monday");
        break;
    case 2:
        console.log("Tuesday");
        break;
    default:
        console.log("Invalid day");
}

    If Statement

    • Executes a block of code if a specified condition is true.
    • Syntax: 
      if (condition) {
    // code to execute
}
    • Example with else: 
      let score = 50;
if (score >= 60) {
    console.log("You passed.");
} else {
    console.log("You failed.");
}

    If...Else Statement

    • Executes one block if true, another if false.
    • Syntax: 
      if (condition) {
    // true block
} else {
    // false block
}
    • Basic example: 
      let number = 10;
if (number % 2 === 0) {
    console.log("The number is even.");
} else {
    console.log("The number is odd.");
}

    If...Else If Statement

    • Evaluates multiple conditions in sequence for greater flexibility.
    • Syntax: 
      if (condition1) {
    // block for condition1
} else if (condition2) {
    // block for condition2
}
    • Example of a grading system: 
      let marks = 82;
if (marks >= 90) {
    console.log("Grade: A");
} else if (marks >= 80) {
    console.log("Grade: B");
} else if (marks >= 70) {
    console.log("Grade: C");
} else if (marks >= 60) {
    console.log("Grade: D");
} else {
    console.log("Grade: F");
}

    Nested If Statement

    • Allows evaluation of multiple conditions hierarchically.
    • Syntax: 
      if (condition1) {
    if (condition2) {
        // code for both conditions true
    } else {
        // code for condition1 true, condition2 false
    }
} else {
    // code for condition1 false
}
    • Example: 
      let age = 25;
let hasMembership = true;
if (age >= 18) {
    if (hasMembership) {
        console.log("Access granted to the VIP lounge.");
    } else {
        console.log("Access granted to the general area.");
    }
} else {
    console.log("Access denied. You must be at least 18 years old.");
}

    Switch Statement

    • Organizes execution based on the value of an expression.
    • Syntax: 
      switch (expression) {
    case value1:
        // block for value1
        break;
    default:
        // block if no case matches
}
    • Example for user role access: 
      let role = "admin";
switch (role) {
    case "admin":
        console.log("Access to all features.");
        break;
    case "editor":
        console.log("Access to edit content.");
        break;
    default:
        console.log("No access.");
}

    Looping Statements

    • Enable execution of code blocks repeatedly based on conditions; main types are for, while, and do...while.

    For Loop

    • Executes a block of code a specified number of times; ideal when iterations are anticipated.
    • Syntax: 
      for (initialization; condition; increment/decrement) {
    // code to execute
}
    • Example of summing numbers (incomplete in original text).

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    Description

    This quiz focuses on selection statements in JavaScript, including if-else and switch statements. It evaluates your understanding of how these statements make decisions within a program by executing particular code blocks based on specified conditions. Test your knowledge with various examples and scenarios.

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