未捕获的类型错误：无法在加号 (js.js:52) 处设置 null 的属性“值”

Question

Id dind't work ! The javascript said that Uncaught TypeError: Cannot set property 'value' of null at plus (js.js:52)

 var count = 1; var countEl = document.getElementById("count"); function plus() { count++; countEl.value = count; } function minus() { if (count > 1) { count--; countEl.value = count; } }

 <div id="input_div"> <input type="text" size="25" value="1" id="count"> <input type="button" value="-" id="moins" onclick="minus()"> <input type="button" value="+" id="plus" onclick="plus()"> </div>

     <div class="col-md-3 py-5">
      <button type="button" class="btn bg-light border rounded-circle">
      <i class="fas fa fa-minus" onclick="minus()"></i></button>
      <input type="text" id="count" value="<?php echo $pro_quantity?>" class="form-control w-25 d-inline">
      <button type="button" class="btn bg-light border rounded-circle">
      <i id="plus" class="fas fa fa-plus" onclick="plus()"></i></button>
     </div>

Answer 1

It's possible that you are not loading your script as <script src="yourfile.js" defer></script> , with that defer attribute in place.

If not, add that to your HTML, because your code is querying the DOM, and so you only want to do that after the DOM has been created . The defer attribute guarantees that will be the case .