adding onClick event to JavaScript for loop

Question

What I am trying to do is to create an App in which there are 26 boxes with ids case0, case1, case2 and so on. When clicked, these should add class \'black\' to respective item0

Answer 1

The onclick function should get the ID of the element that was clicked. Then replace case with item to get the corresponding item, and pass that as an argument to clickCase().

The reason only the last item is clickable is because you're rewriting document.getElementById("casePanel").innerHTML each time through the loop. This recreates all the elements, so all the previous elements no longer have their click handlers.

You can use insertAdjacentHTML() to add HTML to an element without reparsing what it already contains.

let num = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25];
let guess = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25];
let i, x;
let arrayShuffle = function(arr) {
  let newPos, temp;
  for (let i = arr.length - 1; i > 0; i--) {
    newPos = Math.floor(Math.random() * i + 1);
    temp = arr[i],
      arr[i] = arr[newPos];
    arr[newPos] = temp;
  }
  return arr;
};

let numRandom = arrayShuffle(guess);
suitCase();

function suitCase() {
  for (x = 0; x < num.length; x++) {
    document.getElementById("casePanel").insertAdjacentHTML('beforeend', "<a href=\"#\" id=\"case" + numRandom[x] + "\"><div class=\"case\"><span>" + num[x] + "</span></div></a>");
    document.getElementById('case' + numRandom[x]).onclick = function() {
      clickCase(this.id.replace('case', 'item'));
    }
  }
};

function clickCase(id) {
  document.getElementById(id).classList.add('black');
}

.black {
  background-color: blue;
}

<div class="container">
  <header>
    <h1>This is a sample title for this nice suitcase casino</h1>
  </header>

  <main class="wrap">
    <!-- Left price panel -->
    <div class="left-panel">
      <ul>
        <li id="item0">$.01</li>
        <li id="item1">$1</li>
        <li id="item2">$5</li>
        <li id="item3">$10</li>
        <li id="item4">$25</li>
        <li id="item5">$50</li>
        <li id="item6">$75</li>
        <li id="item7">$100</li>
        <li id="item8">$200</li>
        <li id="item9">$300</li>
        <li id="item10">$400</li>
        <li id="item11">$500</li>
        <li id="item12">$750</li>
      </ul>
    </div>
    <!-- ./Left price panel -->

    <div class="case-panel" id="casePanel">

    </div>

    <!-- Right price panel -->
    <div class="right-panel">
      <ul>
        <li id="item13">$1000</li>
        <li id="item14">$5000</li>
        <li id="item15">$10,000</li>
        <li id="item16">$25,000</li>
        <li id="item17">$50,000</li>
        <li id="item18">$75,000</li>
        <li id="item19">$100,000</li>
        <li id="item20">$200,000</li>
        <li id="item21">$300,000</li>
        <li id="item22">$400,000</li>
        <li id="item23">$500,000</li>
        <li id="item24">$750,000</li>
        <li id="item25">$1,000,000</li>
      </ul>
    </div>
    <!-- ./Right price panel -->
  </main>

  <footer></footer>
</div>