js怎么获取value值

<input type="text" id="myInput" value="Hello World!">

// 使用ID获取元素
var inputValue = document.getElementById('myInput').value;
console.log(inputValue); // 输出: Hello World!

// 或者使用querySelector获取元素
var inputValue = document.querySelector('#myInput').value;
console.log(inputValue); // 输出: Hello World!

<select id="mySelect">
  <option value="option1">Option 1</option>
  <option value="option2" selected>Option 2</option>
  <option value="option3">Option 3</option>
</select>

// 获取选中的<option>的value值
var selectValue = document.getElementById('mySelect').value;
console.log(selectValue); // 输出: option2

<input type="radio" name="gender" value="male"> Male
<input type="radio" name="gender" value="female" checked> Female

// 获取选中的单选按钮的值
var radios = document.getElementsByName('gender');
for (var i = 0; i < radios.length; i++) {
  if (radios[i].checked) {
    var genderValue = radios[i].value;
    console.log(genderValue); // 输出: female
    break;
  }
}

<input type="checkbox" id="myCheckbox" value="checkedValue" checked>

// 获取复选框的值
var checkbox = document.getElementById('myCheckbox');
if (checkbox.checked) {
  var checkboxValue = checkbox.value;
  console.log(checkboxValue); // 输出: checkedValue
}