CODEWITHSUNDEEP
javascripthtmldomfrontenddom-events
reddy zombie
reddy zombie

Reputation: 24

Function calls not working in Event listeners

I don't know why this code is not working, neither it is throwing any Error.

function rotateArray(arr){
    return function(){
        var newMod = [];
        for(let i = 0; i<arr.length; i++){
            if(i===0){
                newMod[i] = arr[arr.length - 1];
            }else{
                newMod[i] = arr[i-1];   
            }
        }
        
        return arr = newMod;
    }
}
var btns = {
      btn1: 1,
      btn2: 2,
      btn3: 3,
      btn6: 6,
      btn9: 9,
      btn8: 8,
      btn7: 7,
      btn4: 4,
 }

var rotfunc = rotateArray([1,2,3,6,9,8,7,4]);

document.getElementById('btn5').addEventListener('click',() => {
  let rot = rotfunc()
  for(let i in btns){
      btns[i] = rot.shift();
  }
  for(let i in btns){
      document.getElementById(i).innerHTML = btns[i];  
  }
});
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>Buttons Grid</title>
        <style type="text/css">
            .buttonContainer {
                width: 75%;
            }
            .buttonContainer > .buttonClass {
                    width: 30%;
                    height: 48px;
                    font-size: 24px;
            }
        </style>
    </head>
    <body>
        <div class = "buttonContainer" id = "btns">
            <button id = "btn1" class = "buttonClass">1</button>        
            <button id = "btn2" class = "buttonClass">2</button>
            <button id = "btn3" class = "buttonClass">3</button>
            <button id = "btn4" class = "buttonClass">4</button>        
            <button id = "btn5" class = "buttonClass">5</button>
            <button id = "btn6" class = "buttonClass">6</button>
            <button id = "btn7" class = "buttonClass">7</button>        
            <button id = "btn8" class = "buttonClass">8</button>
            <button id = "btn9" class = "buttonClass">9</button>
        </div>
        <script src="script.js" type="text/javascript"></script>
    </body>
</html>

I am trying to rotate outer circle of Numbers clockwise when clicking on button-5. But it only happens one and then I am losing all values in my 'rot' array. Maybe I am missing something. Can anyone help?

Upvotes: 1

Views: 37

Answers (1)

Barmar
Barmar

Reputation: 780974

When you call rot.shift(), you're modifying the array that's saved in the rotfunc closure. So the next time you call rotfunc(), the array is empty.

Make a copy of the array before modifying it, using the slice() method.

function rotateArray(arr){
    return function(){
        var newMod = [];
        for(let i = 0; i<arr.length; i++){
            if(i===0){
                newMod[i] = arr[arr.length - 1];
            }else{
                newMod[i] = arr[i-1];   
            }
        }
        
        return arr = newMod;
    }
}
var btns = {
      btn1: 1,
      btn2: 2,
      btn3: 3,
      btn6: 6,
      btn9: 9,
      btn8: 8,
      btn7: 7,
      btn4: 4,
 }

var rotfunc = rotateArray([1,2,3,6,9,8,7,4]);

document.getElementById('btn5').addEventListener('click',() => {
  let rot = rotfunc().slice()
  let rot_index = 0;
  for(let i in btns){
      btns[i] = rot.shift();
  }
  for(let i in btns){
      document.getElementById(i).innerHTML = btns[i];  
  }
});
<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>Buttons Grid</title>
        <style type="text/css">
            .buttonContainer {
                width: 75%;
            }
            .buttonContainer > .buttonClass {
                    width: 30%;
                    height: 48px;
                    font-size: 24px;
            }
        </style>
    </head>
    <body>
        <div class = "buttonContainer" id = "btns">
            <button id = "btn1" class = "buttonClass">1</button>        
            <button id = "btn2" class = "buttonClass">2</button>
            <button id = "btn3" class = "buttonClass">3</button>
            <button id = "btn4" class = "buttonClass">4</button>        
            <button id = "btn5" class = "buttonClass">5</button>
            <button id = "btn6" class = "buttonClass">6</button>
            <button id = "btn7" class = "buttonClass">7</button>        
            <button id = "btn8" class = "buttonClass">8</button>
            <button id = "btn9" class = "buttonClass">9</button>
        </div>
        <script src="script.js" type="text/javascript"></script>
    </body>
</html>

Upvotes: 2

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