The following Node module returns “undefined”, but why?

Below is a module that takes one argument, a number, and then either adds or subtracts a const, magicNumber, from it depending on whether or not the number is even or odd, respectively. When I run this code, however, I simply get "undefined." What am I doing wrong?

module.exports = (number) => {



    let answer;  //Answer is declared in the global scope

    const magicNumber = 5;  //magicNumber is declared in the global scope



    if (number % 2) {  //If the number is even

        add(number);  //run the number through the add function

    } else {  //otherwise run the number through the subtract function

        subtract(number);

    }



    function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number + magicNumber;

        return answer;

    }



    function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number - magicNumber;

        return answer;

    }

};

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

3

Your function isn't returning anything, so the return value is undefined by default (also, comments need to be delimited with /* / */ or, on a single line, with // (* alone won't work)

– CertainPerformance
Nov 23 '18 at 1:58

You need to return something from your function, like return add(number); and return subtract(number)

– Paulpro
Nov 23 '18 at 2:54

It is difficult to understand if the code not shown as code is intentional or not (e.g. the first line "module.exports..." and the final line "};" are not displaying as code in your question. Your question should also include the code you're using to call the module.

– bob
Nov 23 '18 at 2:56

add a comment |

module.exports = (number) => {



    let answer;  //Answer is declared in the global scope

    const magicNumber = 5;  //magicNumber is declared in the global scope



    if (number % 2) {  //If the number is even

        add(number);  //run the number through the add function

    } else {  //otherwise run the number through the subtract function

        subtract(number);

    }



    function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number + magicNumber;

        return answer;

    }



    function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number - magicNumber;

        return answer;

    }

};

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

3

Your function isn't returning anything, so the return value is undefined by default (also, comments need to be delimited with /* / */ or, on a single line, with // (* alone won't work)

– CertainPerformance
Nov 23 '18 at 1:58

You need to return something from your function, like return add(number); and return subtract(number)

– Paulpro
Nov 23 '18 at 2:54

It is difficult to understand if the code not shown as code is intentional or not (e.g. the first line "module.exports..." and the final line "};" are not displaying as code in your question. Your question should also include the code you're using to call the module.

– bob
Nov 23 '18 at 2:56

add a comment |

module.exports = (number) => {



    let answer;  //Answer is declared in the global scope

    const magicNumber = 5;  //magicNumber is declared in the global scope



    if (number % 2) {  //If the number is even

        add(number);  //run the number through the add function

    } else {  //otherwise run the number through the subtract function

        subtract(number);

    }



    function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number + magicNumber;

        return answer;

    }



    function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number - magicNumber;

        return answer;

    }

};

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

module.exports = (number) => {



    let answer;  //Answer is declared in the global scope

    const magicNumber = 5;  //magicNumber is declared in the global scope



    if (number % 2) {  //If the number is even

        add(number);  //run the number through the add function

    } else {  //otherwise run the number through the subtract function

        subtract(number);

    }



    function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number + magicNumber;

        return answer;

    }



    function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

        answer = number - magicNumber;

        return answer;

    }

};

javascript return return-value node-modules

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

edited Nov 23 '18 at 6:20

Abhishek Soni

1,19911232

asked Nov 23 '18 at 1:57

user10693340

112

asked Nov 23 '18 at 1:57

user10693340

112

asked Nov 23 '18 at 1:57

user10693340

112

3

Your function isn't returning anything, so the return value is undefined by default (also, comments need to be delimited with /* / */ or, on a single line, with // (* alone won't work)

– CertainPerformance
Nov 23 '18 at 1:58

You need to return something from your function, like return add(number); and return subtract(number)

– Paulpro
Nov 23 '18 at 2:54

It is difficult to understand if the code not shown as code is intentional or not (e.g. the first line "module.exports..." and the final line "};" are not displaying as code in your question. Your question should also include the code you're using to call the module.

– bob
Nov 23 '18 at 2:56

add a comment |

3

Your function isn't returning anything, so the return value is undefined by default (also, comments need to be delimited with /* / */ or, on a single line, with // (* alone won't work)

– CertainPerformance
Nov 23 '18 at 1:58

You need to return something from your function, like return add(number); and return subtract(number)

– Paulpro
Nov 23 '18 at 2:54

It is difficult to understand if the code not shown as code is intentional or not (e.g. the first line "module.exports..." and the final line "};" are not displaying as code in your question. Your question should also include the code you're using to call the module.

– bob
Nov 23 '18 at 2:56

Your function isn't returning anything, so the return value is undefined by default (also, comments need to be delimited with /* / */ or, on a single line, with // (* alone won't work)

– CertainPerformance
Nov 23 '18 at 1:58

You need to return something from your function, like return add(number); and return subtract(number)

– Paulpro
Nov 23 '18 at 2:54

It is difficult to understand if the code not shown as code is intentional or not (e.g. the first line "module.exports..." and the final line "};" are not displaying as code in your question. Your question should also include the code you're using to call the module.

– bob
Nov 23 '18 at 2:56

add a comment |

1 Answer
1

active

oldest

votes

Your exported block is not returning anything hence it’s undefined by default.

module.exports = (number) => {

let answer;  //Answer is declared in the global scope

const magicNumber = 5;  //magicNumber is declared in the global scope



if (number % 2) {  //If the number is even

    return add(number);  //you should return here as well

} else {  //otherwise run the number through the subtract function

    return subtract(number);//you should return here as well 

}



function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number + magicNumber;

    return answer;

}



function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number - magicNumber;

    return answer;

}

};

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

add a comment |

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1 Answer
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votes

Your exported block is not returning anything hence it’s undefined by default.

module.exports = (number) => {

let answer;  //Answer is declared in the global scope

const magicNumber = 5;  //magicNumber is declared in the global scope



if (number % 2) {  //If the number is even

    return add(number);  //you should return here as well

} else {  //otherwise run the number through the subtract function

    return subtract(number);//you should return here as well 

}



function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number + magicNumber;

    return answer;

}



function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number - magicNumber;

    return answer;

}

};

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

add a comment |

Your exported block is not returning anything hence it’s undefined by default.

module.exports = (number) => {

let answer;  //Answer is declared in the global scope

const magicNumber = 5;  //magicNumber is declared in the global scope



if (number % 2) {  //If the number is even

    return add(number);  //you should return here as well

} else {  //otherwise run the number through the subtract function

    return subtract(number);//you should return here as well 

}



function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number + magicNumber;

    return answer;

}



function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number - magicNumber;

    return answer;

}

};

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

add a comment |

Your exported block is not returning anything hence it’s undefined by default.

module.exports = (number) => {

let answer;  //Answer is declared in the global scope

const magicNumber = 5;  //magicNumber is declared in the global scope



if (number % 2) {  //If the number is even

    return add(number);  //you should return here as well

} else {  //otherwise run the number through the subtract function

    return subtract(number);//you should return here as well 

}



function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number + magicNumber;

    return answer;

}



function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number - magicNumber;

    return answer;

}

};

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

Your exported block is not returning anything hence it’s undefined by default.

module.exports = (number) => {

let answer;  //Answer is declared in the global scope

const magicNumber = 5;  //magicNumber is declared in the global scope



if (number % 2) {  //If the number is even

    return add(number);  //you should return here as well

} else {  //otherwise run the number through the subtract function

    return subtract(number);//you should return here as well 

}



function add(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number + magicNumber;

    return answer;

}



function subtract(number){  //Function takes the number as argument, does the math, and returns the value of answer.

    answer = number - magicNumber;

    return answer;

}

};

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

answered Nov 23 '18 at 3:37

Ravinder Payal

1,4541328

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

add a comment |

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

My logic was that since one or the other function, add() or subtract(), respectively, would inevitably be called and each of those have their own returns, the intended outcome of the code would inevitably be returned. It's confusing to me that return statements would have to drive the continual execution of the code at every step when it seems intuitive that once either of the lines add(number); or subtract(number); are hit, those functions would run and would return values regardless. I'm currently researching this but finding nothing. Is there something fundamental I'm misunderstanding?

– user10693340
Nov 23 '18 at 15:55

In JavaScript and almost all programming languages return statement is block based

– Ravinder Payal
Nov 23 '18 at 15:59

add a comment |

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