How to use a variable in your function from another function (Combination Calculator)-CodePudding

I am new in JS and I'm having difficulty with using a variable from another function to my new function.

the goal is to compute for a combination (combination calculator) but when I use this script code I don't get an output. Please help

var i, num, num2;

function factor() {
  x = 1;
  y = 1;
  num = document.getElementById("num").value;
  for(i = 1; i <= num; i  )  
    {
      x = x * i;
    }
    i = i - 1;  
    document.getElementById("res").innerHTML = "The factorial of the number "   i   " is: "   x ;

  num2 = document.getElementById("num2").value;
  for(i = 1; i <= num2; i  )  
    {
      y = y * i;
    }
    i = i - 1;  
    document.getElementById("res2").innerHTML = "The factorial of the number "   i   " is: "   y ;
  
  }

  function partTwo () {
    
    a = y.factor(num - num2);
    b = x.factor/a;

    document.getElementById("res3").innerHTML = "Answer: " ;

  }

here is the html code

<!--Input-->
        <h2 id="one"> Please enter first value for combination calculation </h2>
        <input type="number" placeholder="Number 1"id="num"> <br> <br>
        <!--Input 2-->
        <h2 id="two"> Please enter second value for combination calculation </h2>
        <input type="number" placeholder="Number 2"id="num2"> <br> <br>

        <!--button-->
        <button onclick="factor()" > ENTER </button>
        <h2 id="res"> </h2>
        <h2 id="res2"> </h2>

        <button onclick="partTwo()" > CALCULATE </button>
        <h2 id="res3"> </h2>

I was supposed to get an output for a combination calculator and need help how to do the second function

CodePudding user response：

You can't use the variables out of their scope or if you want to use this variable pass through the parameter try this:

    var i, num, num2;

function factor() {
  x = 1;
  y = 1;
  num = document.getElementById("num").value;
  for(i = 1; i <= num; i  )  
    {
      x = x * i;
    }
    i = i - 1;  
    document.getElementById("res").innerHTML = "The factorial of the number "   i   " is: "   x ;

  num2 = document.getElementById("num2").value;
  for(i = 1; i <= num2; i  )  
    {
      y = y * i;
    }
    i = i - 1;  
    document.getElementById("res2").innerHTML = "The factorial of the number "   i   " is: "   y ;
    partTwo(x,y)
  
  }

  function partTwo (x,y) {
    
    a = y.factor(num - num2);
    b = x.factor/a;

    document.getElementById("res3").innerHTML = "Answer: " ;

  }

CodePudding user response：

It is possible to use variables from one function to another if you're going to make it a global variable.

But based on the format of your partTwo() function, I believe what you want to learn here is the use of "class" in JavaScript.

I reconstructed your code and changed a few stuff in your HTML and JavaScript.

<h2 id="one"> Please enter first value for combination calculation </h2> 
<input type="number" placeholder="Number 1" id="num1"> <br> <br>
<!--Input 2-->
<h2 id="two"> Please enter second value for combination calculation </h2>
<input type="number" placeholder="Number 2" id="num2"> <br> <br>
<!--These buttons were replaced by ID so that I can add an event listener in the JS instead of onclick tag-->
<button id="enter"> ENTER </button>  
<h2 id="res"> </h2>
<h2 id="res2"> </h2>
<button id="calculate"> CALCULATE </button>
<h2 id="res3"> </h2>

Here's the JS code using class instead of function:

class myfactor {
  constructor(num1, num2) {
    this.num1 = num1;
    this.num2 = num2;
  }
  x() {
    var xval = 1;
    for(var i = 1; i <= this.num1; i  )  
    {
      xval = xval * i;
    }
    i = i - 1;
    return xval;
  }
  
  y() {
    var yval = 1;
    for(var i = 1; i <= this.num2; i  ){
      yval = yval * i;
    }
    i = i - 1;
    return yval;
  }
}

And here's the rest of the code, wherein you can find the "click" events for both "enter" and "calculate" button:

var factor;
var num1;
var num2;

document.getElementById("enter").addEventListener("click", function(){
  num1 = document.getElementById("num1").value;
  num2 = document.getElementById("num2").value;
  
  factor = new myfactor(num1, num2);
  
  document.getElementById("res").innerHTML = "The factorial of the number "   num1   " is: "   factor.x();
  document.getElementById("res2").innerHTML = "The factorial of the number "   num2   " is: "   factor.y();
});

document.getElementById("calculate").addEventListener("click", function(){
  var a = factor.y() * (num1 - num2);
  var b = factor.x() / a;
  document.getElementById("res3").innerHTML = "Answer: "   b;
});

It is unclear in your question what you are trying to output here, but I just used your variable b as the final output since it has the last formula in the code.