Having trouble with your if statement in JavaScript?

Question

Having trouble with your if statement in JavaScript?

I am currently working on a menu system using an array and if statements for each option. However, I have encountered an issue where selecting certain options in a specific order does not produce the desired result.

For instance, when adding credit followed by trying to view the current credit, it fails to display the correct information.

Any assistance or suggestions would be greatly appreciated!

Best Regards.

var readlineSync = require('readline-sync')
var currentCredit = 0;
var removeCredit = 0;

menu = [];
menu[0] = "Purchase a product";
menu[1] = "View your credit";
menu[2] = "Add credit";
menu[3] = "Retrieve a refund";

index = readlineSync.keyInSelect(menu, 'Please select an option');

if (index == [1]) {
console.log("Your current credit balance is: £", currentCredit);
index = readlineSync.keyInSelect(menu, 'Please select an option');
}

if (index == [2]) {
var addedCredit = readlineSync.questionInt('How much credit would you like to add? ');
currentCredit += addedCredit;
console.log("Your total credit balance now is: £" + currentCredit);
index = readlineSync.keyInSelect(menu, 'Please select an option');
}

if (index == [3]) {
var removedCredits = readlineSync.questionInt('How much credit do you want to remove? ');
currentCredit -= removedCredits;
console.log("The chosen credits have been removed. Your remaining available credit is: £" + currentCredit);
index = readlineSync.keyInSelect(menu, 'Please select an option');
}

javascript if-statement npm

Answer 1

Answer №1

If you're looking to continuously run your script in a loop, consider the following code:

var idx, points, deductions;
while(true) {
    idx = readlineSync.keyInSelect(menu, 'Select an option:');
    
    if (idx == 1) {
        console.log("Your current credit balance is: £", points);
    }

    if (idx == 2) {
        points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
        console.log("Your updated credit balance is: £" + points);
    }

    if (idx == 3) {
        deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
        console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
    }
}

To exit the loop based on a chosen option, modify the code like this:

var idx, points, deductions;
while((idx = readlineSync.keyInSelect(menu, 'Select an option:')) != 4) {
    if (idx == 1) {
        console.log("Your current credit balance is: £", points);
    }

    if (idx == 2) {
        points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
        console.log("Your updated credit balance is: £" + points);
    }

    if (idx == 3) {
        deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
        console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
    }
}

In this scenario, the number 4 serves as the exit option. Also note the use of "loose" equality for comparison since the return type of keyInSelect is not certain.

If you find the previous syntax confusing, here's an alternate version with improved readability:

var idx, points, deductions;
do {
    idx = readlineSync.keyInSelect(menu, 'Select an option:');
    
    switch(idx) {
        case 1:
            console.log("Your current credit balance is: £", points);
            break;

        case 2:
            points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
            console.log("Your updated credit balance is: £" + points);
            break;

        case 3:
            deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
            console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
            break;
    }
} while(idx != 4);

Answer 2

If you're looking to continuously run your script in a loop, consider the following code:

var idx, points, deductions;
while(true) {
    idx = readlineSync.keyInSelect(menu, 'Select an option:');
    
    if (idx == 1) {
        console.log("Your current credit balance is: £", points);
    }

    if (idx == 2) {
        points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
        console.log("Your updated credit balance is: £" + points);
    }

    if (idx == 3) {
        deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
        console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
    }
}

To exit the loop based on a chosen option, modify the code like this:

var idx, points, deductions;
while((idx = readlineSync.keyInSelect(menu, 'Select an option:')) != 4) {
    if (idx == 1) {
        console.log("Your current credit balance is: £", points);
    }

    if (idx == 2) {
        points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
        console.log("Your updated credit balance is: £" + points);
    }

    if (idx == 3) {
        deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
        console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
    }
}

In this scenario, the number 4 serves as the exit option. Also note the use of "loose" equality for comparison since the return type of keyInSelect is not certain.

If you find the previous syntax confusing, here's an alternate version with improved readability:

var idx, points, deductions;
do {
    idx = readlineSync.keyInSelect(menu, 'Select an option:');
    
    switch(idx) {
        case 1:
            console.log("Your current credit balance is: £", points);
            break;

        case 2:
            points = readlineSync.questionInt('Enter the amount of credit you want to add: ');
            console.log("Your updated credit balance is: £" + points);
            break;

        case 3:
            deductions = readlineSync.questionInt('Enter the amount of credit you want to deduct: ');
            console.log("Deductions made. Your remaining credit balance is: £" + (points - deductions));
            break;
    }
} while(idx != 4);

Answer 3

Answer №2

Consider eliminating the brackets within your conditionals, for example:

if (count == 3)

Answer 4

Consider eliminating the brackets within your conditionals, for example:

if (count == 3)

Answer 5

Answer №3

Solving the issue is quite straightforward. The earlier if conditions will not be executed as the program flow cannot reverse. To address this, all the if conditions should be placed within a designated function. Upon receiving a new input, invoke this function so that each and every if condition is validated. The flow of control progresses from one line to the next without returning to a previous line unless inside a function (by calling it) or loop.

If you opt for a function, you have the option to call the function again ensuring that all if statements are reevaluated.

For instance:

if(i==1)
alert("one");
if(i==2)
alert("two");
 i=1;
if(i==3)
alert("three");

The program does not revisit the preceding if statement, hence no alert will be displayed.

function alerts()
{

if(i==1)
alert("one");
if(i==2)
alert("two");
 i=1;
alerts();
if(i==3)
}

In this scenario, only an alert box with "one" will pop up since the function has been invoked, causing prior conditions to be reassessed as well.

Answer 6

Solving the issue is quite straightforward. The earlier if conditions will not be executed as the program flow cannot reverse. To address this, all the if conditions should be placed within a designated function. Upon receiving a new input, invoke this function so that each and every if condition is validated. The flow of control progresses from one line to the next without returning to a previous line unless inside a function (by calling it) or loop.

If you opt for a function, you have the option to call the function again ensuring that all if statements are reevaluated.

For instance:

if(i==1)
alert("one");
if(i==2)
alert("two");
 i=1;
if(i==3)
alert("three");

The program does not revisit the preceding if statement, hence no alert will be displayed.

function alerts()
{

if(i==1)
alert("one");
if(i==2)
alert("two");
 i=1;
alerts();
if(i==3)
}

In this scenario, only an alert box with "one" will pop up since the function has been invoked, causing prior conditions to be reassessed as well.

Having trouble with your if statement in JavaScript?

Answer №1

Answer №2

Answer №3

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