Utilizing Mathematical Calculations Across Multiple JavaScript Functions

Question

Utilizing Mathematical Calculations Across Multiple JavaScript Functions

Just dipping my toes into the Javascript realm and attempting to crack this task my instructor assigned. Here's what he expects from us:

Create a function to kickstart the program. Name it start()
Inside the start() function, invoke a function named getValue()
The getValue() function should retrieve a number from the user for squaring.
Add another function inside the start() function called makeSquare()
The makeSquare() function will square the user-provided number obtained in the getValue() function.
Make sure to display the squared result within the makeSquare() function.

Here's what I managed to put together so far:

function start() {

    getValue();
    getSquare();
}

function getValue() {

    var num = prompt("Please enter a number")
}

function getSquare() {

    var squaredNum = Math.pow(num)
    document.write(squaredNum)
}

start()

This activity doesn't involve any HTML tags, just grappling with getting the prompt box to work. Any thoughts on whether I'm handling variables correctly?

javascript

Answer 1

Answer №1

You were almost there, but it appears that you may need a better grasp on scoping and how to correctly utilize the pow function.

Understanding Math.pow:

Math.pow requires two parameters: the base and the exponent. In your example, only the base was provided. This can result in issues as the function will return undefined and assign it to b. Here is the correct way to square a number using this function:

Math.pow(a, 2);

Scope Rules:

Each function has its own scope. While you can access variables and functions created outside the function from inside it, you cannot reach those created within another function. Consider the following example:

var c = 5;

function foo() {
   var a = c;
}

var b = a; // This will not work as 'a' is no longer accessible after the function ends.

Functions can be seen as private entities, except for the ability to return values using the return keyword. The value next to this keyword becomes the function's return value:

function foo() {
    return 5;
}

var a = foo(); // Now 'a' equals 5

The error in your code lies in attempting to access

// ...
var b = Math.pow(a)

Can you spot the mistake now? Since 'a' is defined within the function, it cannot be accessed outside of it.

To fix this issue, the code should be revised as follows (Remember to always use semicolons where necessary):

function start() {
    getSquare();
}

function getValue() {
    var a = prompt("Number please");
    return a;
}

function getSquare() {
    var b = Math.pow(getValue(), 2);
    document.write(b);
}

start();

Answer 2

You were almost there, but it appears that you may need a better grasp on scoping and how to correctly utilize the pow function.

Understanding Math.pow:

Math.pow requires two parameters: the base and the exponent. In your example, only the base was provided. This can result in issues as the function will return undefined and assign it to b. Here is the correct way to square a number using this function:

Math.pow(a, 2);

Scope Rules:

Each function has its own scope. While you can access variables and functions created outside the function from inside it, you cannot reach those created within another function. Consider the following example:

var c = 5;

function foo() {
   var a = c;
}

var b = a; // This will not work as 'a' is no longer accessible after the function ends.

Functions can be seen as private entities, except for the ability to return values using the return keyword. The value next to this keyword becomes the function's return value:

function foo() {
    return 5;
}

var a = foo(); // Now 'a' equals 5

The error in your code lies in attempting to access

// ...
var b = Math.pow(a)

Can you spot the mistake now? Since 'a' is defined within the function, it cannot be accessed outside of it.

To fix this issue, the code should be revised as follows (Remember to always use semicolons where necessary):

function start() {
    getSquare();
}

function getValue() {
    var a = prompt("Number please");
    return a;
}

function getSquare() {
    var b = Math.pow(getValue(), 2);
    document.write(b);
}

start();

Answer 3

Answer №2

Since this is a homework assignment, I won't provide the answer outright but instead offer some hints.

In JavaScript, variables are scoped within functions. This means that a variable like var a declared inside the function getValue is only accessible within that function.

You have the ability to use return to send back a value from a function.

Remember, functions are considered first-class objects in JavaScript. This allows you to pass them as arguments to other functions and ultimately call them within those functions.

Answer 4

Since this is a homework assignment, I won't provide the answer outright but instead offer some hints.

In JavaScript, variables are scoped within functions. This means that a variable like var a declared inside the function getValue is only accessible within that function.

You have the ability to use return to send back a value from a function.

Remember, functions are considered first-class objects in JavaScript. This allows you to pass them as arguments to other functions and ultimately call them within those functions.

Answer 5

Answer №3

Is my utilization of variables causing issues?

Absolutely, that appears to be the root of your troubles. Variables in various programming languages are bound by a specific scope, dictating where they can be accessed. In this scenario, a and b act as local variables within the functions getValue() and makeSquare() respectively. This means their accessibility is confined to the function they belong to.

In general, this practice has its benefits. Utilizing restricted scopes for your variables enhances the clarity of data transmission throughout your program. It's preferable to utilize return values and parameters for passing data among functions instead of resorting to global variables:

function commence() {
    var a = getValue();
    makeSquare(a);
}

// Obtain a value inputted by the user
function getValue() {
    return prompt("Please enter a number")
}

// Display the square of the provided `a` parameter within the document
function makeSquare(a) {
    var b = Math.pow(a)
    document.write(b)
}

Answer 6

Is my utilization of variables causing issues?

Absolutely, that appears to be the root of your troubles. Variables in various programming languages are bound by a specific scope, dictating where they can be accessed. In this scenario, a and b act as local variables within the functions getValue() and makeSquare() respectively. This means their accessibility is confined to the function they belong to.

In general, this practice has its benefits. Utilizing restricted scopes for your variables enhances the clarity of data transmission throughout your program. It's preferable to utilize return values and parameters for passing data among functions instead of resorting to global variables:

function commence() {
    var a = getValue();
    makeSquare(a);
}

// Obtain a value inputted by the user
function getValue() {
    return prompt("Please enter a number")
}

// Display the square of the provided `a` parameter within the document
function makeSquare(a) {
    var b = Math.pow(a)
    document.write(b)
}

Answer 7

Answer №4

Ensure that your getValue() function returns the value before passing it to the getSquare() function.
It is advisable to terminate each line with a ;.
To convert user input into a number, consider using parseFloat(string).
When using Math.pow, remember to pass 2 as the second argument to calculate the square.

I have included explanatory comments in your code:

function start() {
    // Capture the returned value
    var value = getValue();
    // Pass the value to the square-function
    getSquare(value);
}

function getValue() {
    // Convert user input into a number and return    
    return parseFloat(prompt("Enter a number"));
}

// Allow the square-function to accept the user input
function getSquare(a) {  
    // Utilize Math.pow with a power of 2 as the second argument
    var b = Math.pow(a, 2);
    document.write(b);
}

start();

An alternative approach

In JavaScript, variable scope is determined by functions. Declaring a variable with var restricts its access to that function and its child functions. Without var or at a global level, the variable becomes accessible globally across the page.

You could make the variable a in getValue() global by omitting the var keyword, allowing it to be accessed within getSquare() as attempted in your example.

This practice is not recommended due to namespace pollution and potential conflicts if another script uses a global variable of the same name, leading to unexpected behavior.

Answer 8

Ensure that your getValue() function returns the value before passing it to the getSquare() function.
It is advisable to terminate each line with a ;.
To convert user input into a number, consider using parseFloat(string).
When using Math.pow, remember to pass 2 as the second argument to calculate the square.

I have included explanatory comments in your code:

function start() {
    // Capture the returned value
    var value = getValue();
    // Pass the value to the square-function
    getSquare(value);
}

function getValue() {
    // Convert user input into a number and return    
    return parseFloat(prompt("Enter a number"));
}

// Allow the square-function to accept the user input
function getSquare(a) {  
    // Utilize Math.pow with a power of 2 as the second argument
    var b = Math.pow(a, 2);
    document.write(b);
}

start();

An alternative approach

In JavaScript, variable scope is determined by functions. Declaring a variable with var restricts its access to that function and its child functions. Without var or at a global level, the variable becomes accessible globally across the page.

You could make the variable a in getValue() global by omitting the var keyword, allowing it to be accessed within getSquare() as attempted in your example.

This practice is not recommended due to namespace pollution and potential conflicts if another script uses a global variable of the same name, leading to unexpected behavior.

Answer 9

Answer №5

Give this a shot.

<script type="type/javascript">
function begin(){
createSquare(obtainValue());
}

function obtainValue(){
return prompt("input a number");
}

function createSquare(b){
var output=Math.pow(b,2);
alert(output);
}
begin();
</script>

Answer 10

Give this a shot.

<script type="type/javascript">
function begin(){
createSquare(obtainValue());
}

function obtainValue(){
return prompt("input a number");
}

function createSquare(b){
var output=Math.pow(b,2);
alert(output);
}
begin();
</script>

Utilizing Mathematical Calculations Across Multiple JavaScript Functions

Answer №1

Understanding Math.pow:

Scope Rules:

Answer №2

Answer №3

Answer №4

Answer №5

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