Javascript issue with functions not changing the inputs

Question

I am trying to use a function to change an input to what is set within the parameters. The checks work fine in determining if the input is correct, but the don't change the original inputs. I feel like it is something small I am missing, is anyone able to help? Here is my code:

var x = prompt("enter number");
var y = prompt("enter number");

function isThisRowNumberCorrect(number1){
if (isNaN(number1) === true){
    alert("Please choose a row number between 0 and 5!");
    number1 = prompt("Please choose a row number between 0 and 5.")-'';
}
if (number1 > 5){
    alert("Please choose a row number between 0 and 5!");
    number1 = prompt("Please choose a row number between 0 and 5.")-'';
}
if (number1 < 0){
    alert("Please choose a row number between 0 and 5!");
    number1 = prompt("Please choose a row number between 0 and 5.")-'';
}
number1 = number1;
}

function isThisColumnNumberCorrect(number2){
if (isNaN(number2) === true){
    alert("Please choose a column number between 0 and 5!");
    number2 = prompt("Please choose a column number between 0 and 5.")-'';
}
if (number2 > 5){
    alert("Please choose a column number between 0 and 5!");
    number2 = prompt("Please choose a column number between 0 and 5.")-'';
}
if (number2 < 0){
    alert("Please choose a column number between 0 and 5!");
    number2 = prompt("Please choose a column number between 0 and 5.")-'';
}

number2 = number2;
}
isThisRowNumberCorrect(x);
isThisColumnNumberCorrect(y);

console.log(x + "" + y);

Joy · Accepted Answer · 2015-09-01 00:28:04Z

2

The parameters of the two functions are primitive type. When passed into the function, JavaScript engine will create a new copy of the primitive parameters. So setting the value inside the function number2 = number2; will not change the value outside.

You need to return the new value from the function isThisRowNumberCorrect:

return number1;

And call the function like:

x = isThisRowNumberCorrect(x);

answered Sep 1, 2015 at 0:28

Joy

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2 Comments

Havamere Over a year ago

See, I knew it was something simple, this is for a much much larger game code and its been bugging me the last few hours. Thank you

Joy Over a year ago

@Havamere My pleasure :)

StackSlave · Accepted Answer · 2015-09-01 00:53:53Z

0

You are reassigning the result of the prompt to your variable within your functions which then possibly miss conditions. Also, your functions don't return anything. They just create a global variables. Your editor should have a mild warning for assigning the argument to a variable with the same name. Although I advise against using prompt and alert you may want your code to look something like:

function promptRowExample(){
  var p = prompt('Please Choose a Row Between 0 and 5.');
  if(p < 0 || p > 5 || isNaN(p)){
    return promptRowExample();
  }
  return 'The Number '+p+' is a Valid Number!';
}
console.log(promptRowExample());

edited Sep 1, 2015 at 0:53

answered Sep 1, 2015 at 0:45

StackSlave

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