javascript - 我想获取复选框值

Question

它总是说 if (checks[i].checked === true ) 这是我遇到的错误...

我想从复选框值中获取值...

function submitFun() {
  var checks = document.getElementsByClassName('checks')
  var str = "";
  for (let i = 0; i < 3; i++) {

    if (checks[i].checked === true) {
      str += checks[i].value + "";
    }
  }
  alert(str);
}

<div class="container">

  <input type="checkbox" class="checks" value="뜨거워"> hot
  <input type="checkbox" class="checks" value="추워"> clod
  <a href="#" onclick="submitFun();return false;">ok </a>

</div>

Answer 1

当您有两个 ( 2 ) 个复选框时，您将迭代三 ( 3 ) 次，在循环结束时，i将是 2和 check[2]是undefined , 做 i < checks.length而不是 i < 3 :

function submitFun() {
  var checks = document.getElementsByClassName('checks')
  var str = "";

  for (let i = 0; i < checks.length; i++) {
    if (checks[i].checked === true) {
      str += checks[i].value + " ";
    }
  }
  alert(str);
}

<div class="container">
  <input type="checkbox" class="checks" value="hot"> hot
  <input type="checkbox" class="checks" value="cold"> clod
  <a href="#" onclick="submitFun();return false;">ok </a>
</div>