codeup-web-exercises/loop_lecture.html at main · rickmorales7693/codeup-web-exercises · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Loops Lecture</title>
</head>
<body>
<h1>Loops Lecture</h1>

<script>

    "use strict";

    // ================================ WHILE LOOP

    /*
        While loop syntax:

            while (conditionIsTrue) {
                do something...
            }

        Used to repeat a block of code until a condition changes to break the loop
        Likely used when the number of iterations is unknown

        Diagram ***Curriculum***

    */

    // basic example
    let x = 1;
    while(x < 10){
        console.log(x);
        ++x;
    }
    //
    // console.log(1);
    // console.log(2);
    // console.log(3);

    // possible use cases

    while(gameRunning) {
        drawCanvas();
    }

    while(timerOn) { // elsewhere: a button when clicked, sets timer to off
        countUp();
    }


    let password = "Open Sesame";
    let guess = "";
    while(guess !== password) {
        guess = prompt("Please enter the password.");
    }

    // condition never executes

    let x = 10;
    while (x < 5) {
        console.log(x);
        x--;
    }


    // infinitely executes

    let x = 5;
    while (x !== 4) {
        x++;
    }

    // given variable x, while x is less than 100, increment x by 5. x begins at 0. Console log the value of x for each iteration;

    let x = 0;
    while (x < 100) {
        console.log(x);
        x += 5;
    }

    // TODO - write a while loop that prints your name 10 times

    let x = 1;
    while (x <= 10){
        console.log('Rick');
        x++;
    }

    /*
        TODO CHALLENGE - write a function, getNum1To10 that returns a number between 1 and 10 from the user.
          Keep prompting them until a valid number is given
     */
    function getNum1to10(){
        let num = 0;
        while (num < 1 || num > 10) {
            num = prompt('Please enter a number between 1 and 10');
        }
        return num;
    }

    alert(getNum1to10(10));
    // ================================ DO-WHILE LOOP

    /*
        While loop syntax:

            do {
                do something no matter what...
            } while(conditionIsTrue);

        Used to execute a block and code at least once
        and repeat it until the condition is no longer true

        Diagram ***Curriculum***

    */

    // basic example

    let x = 10;
    do {
        alert("This will run.");
    } while (x !== 10);


    // use case

    let password = "";
    do {
        password = prompt("Please enter a valid password.");
    }
    while(password !== 'letmein');

    // The do-while executes at least once


    /*
        TODO - write a do-while loop that will alert the current date and time and
          continue checking with the user if they want to see the latest time.
     */

    let dateQuestion = false;
    do {
        dateQuestion = confirm('Display the current date and time?');
        if (dateQuestion === true) {
            alert(new Date().toLocaleString());
        }
    } while (dateQuestion === false);

    // ================================ FOR LOOP

    /*
        For loop diagram ***Curriculum***

        For loop syntax:

            for (initialization; test; iteration) {
                do something a set number of times
            }

        Used to perform an action based on a number of iterations

    */

    // with incrementer

    for (let i = 1; i < 10; ++i) {
        console.log(i);
    }


    // with decrementer

    for (let i = 20; i >= 10; --i) {
        console.log(i);
    }

    // nested for loops

    for (let i = 0; i <= 10; ++i) {
        console.log("Badgers, badgers, badgers");
        for (let j = 0; j <= 1; ++j) {
            console.log("Mushroom");
        }
    }

    // multiple iterators (less common)

    for (let i = 0, j = 9; i < 10; ++i, --j) {
        console.log("value of i:" + i + " and value of j: " + j);
    }


    // console.log each letter in a given string

    // get length of string

    // let someString = prompt("Enter a word");
    //
    // for (let i = 0; i <= someString.length; i += 1) {
    //     console.log(someString.charAt(i));
    // }

    //TODO - write a for loop that prints all even numbers from 2 to 100

    for (let i = 2; i <= 100; i += 2) {
        console.log(i);
    }

    //TODO - write a for loop that prints all integers from 20 down to 1

    for (let i = 20; i >= 1; --i) {
        console.log(i);
    }

    // ================================ BREAK / CONTINUE

    // break - keyword to end the execution of a loop

    let y = 0;

    while (true) {
        if (y === 10) {
            console.log("End of loop!");
            break;
        }
        ++y;
        console.log(y);
    }

    // web example


    let password = "123";

    while (true) {
        password = prompt("Please enter a valid password: ");
        if (password === "123") {
            break;
        }
    }

    // console.log("Access granted.");

    // game example

    let gameRunning = true;

    let lives = 3;

    while (gameRunning) {
        // play game
        if (lives === 0) {
            console.log("Game over");
            break;
        }
    }


    // output values up to 50 from 0, if value is 25, stop the loop

    let x = 0;

    while (x < 50) {
        if (x === 25) {
            break;
        }
        console.log(x);
        x += 1;
    }


    // continue

    console.log("Continue example");

    let y = 0;

    while (true) {
        y++;
        if (y === 100) {
            console.log("End of loop!");
            break;
        }
        if (y % 5 === 0) {
            continue;
        }
        console.log(y);
    }

    // web example

    /*

        Display a stylized list of weather info by year
        in which a specific geographic region experienced drought conditions.
            Skip any years that do not meet the criteria.
            If the years have already been displayed in the list, continue to the next year.

     */

</script>

</body>
</html>