While loop inside a for loop concatening

Question

when I execute this code it spits out a new row inside the table but it includes the previous iteration along with the newest one. I want all "As" to be in the first row in the main table. And then I want all "Bs" to be in the second , etc, etc. Then for A0, A1, and A2, I want them to be in their own table within the first row, same for B0, B1 in the second row, etc, etc


  



  
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user_1715121 · Answer

Declare this variable var text = ""; inside of the for-loop

var array = [  ["A0---", "A1----", "A2---"],  ["B0----", "B1---"],  ["C0---", "C1---"],  ["D0---", "D1---"]];

for (var i = 0; i < array.length; i++) {
  var text = "";
  var j = 0;
  while (j < array[i].length) {
    text += "" + array[i][j] + "";
    j++;
  }

  document.getElementById(i).innerHTML = text;
}

table,th,td {  border: 1px solid black;}

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user_9515207 · Answer

Initialize the text variable to the empty string inside the first loop instead:

for (var i = 0; i < array.length; i++) {
  let text = '';

But note that you can make your code more functional, shorter, and easier to read by using array methods like .map and forEach rather than using for, while, and manual iteration (better not to have to keep track of indicies):

array.forEach((subArr, i) => {
  const text = subArr.map(item => "" + item + "");
  document.getElementById(i).innerHTML = text.join('');
});

var array = [
  ["A0---", "A1----", "A2---"],
  ["B0----", "B1---"],
  ["C0---", "C1---"],
  ["D0---", "D1---"]
];

array.forEach((subArr, i) => {
  const text = subArr.map(item => "" + item + "");
  document.getElementById(i).innerHTML = text.join('');
});

table,
th,
td {
  border: 1px solid black;
}


  
    gerp gerp
    
      
    
  
  
    gerp gerp
    
      
    
  
  
    gerp gerp
    
      
    
  
  
    gerp gerp

While loop inside a for loop concatening

2 Answers