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How to get the selected state of a radio button using JavaScript

不言Original: 2018-12-05 14:28:529155browse

To use JavaScript to select the status of a radio button, you need to select the checked attribute of the radio button object. This article introduces how to use JavaScript to obtain the selection status of the radio button.

Let’s first look at the value of the checked attribute

true: Select the radio button

false: The radio button is not selected

When getting the radio button in the form

The situation specified by the id attribute

Referring to the id form control in JavaScript

document.forms.(参照表格的id).(参照控件的id)

When referencing the selected state of the radio button through the id

document.forms.(参照表格的id).(参照How to get the selected state of a radio button using JavaScript的id).checked

can also be accessed

document.(参照表格的name).(参照How to get the selected state of a radio button using JavaScript的id).checked

When specified by the name attribute

The controls for text boxes and check boxes can be obtained from the name, but for radio buttons, if they are set to the same radio button group , you cannot use Get from Name because the value of Name is the same. We will check the selection status from the ID introduced earlier.

The code is as follows

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
  <title></title>
  <script type="text/javascript" language="javascript">
    function onHow to get the selected state of a radio button using JavaScriptChange() {
      check1 = document.form1.Radio1.checked;
      check2 = document.form1.Radio2.checked;
      check3 = document.form1.Radio3.checked;
      target = document.getElementById("output");
      if (check1 == true) {
        target.innerHTML = "元素1被选中。<br/>";
      }
      else if (check2 == true) {
        target.innerHTML = "元素2被选中。<br/>";
      }
      else if (check3 == true) {
        target.innerHTML = "元素3被选中。<br/>";
      }
    }
  </script>
</head>
<body>
  <form name="form1" action="">
    <input id="Radio1" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" />
      <label for="Radio1">How to get the selected state of a radio button using JavaScript 元素1</label><br/>
    <input id="Radio2" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" />
      <label for="Radio2">How to get the selected state of a radio button using JavaScript 元素2</label><br />
    <input id="Radio3" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" />
      <label for="Radio3">How to get the selected state of a radio button using JavaScript 元素3</label><br />
  </form>
  <div id="output"></div>
</body>
</html>

Explanation:

  <script type="text/javascript" language="javascript">
    function onHow to get the selected state of a radio button using JavaScriptChange() {
      check1 = document.form1.Radio1.checked;
      check2 = document.form1.Radio2.checked;
      check3 = document.form1.Radio3.checked;
      target = document.getElementById("output");
      if (check1 == true) {
        target.innerHTML = "元素1被选中。<br/>";
      }
      else if (check2 == true) {
        target.innerHTML = "元素2被选中。<br/>";
      }
      else if (check3 == true) {
        target.innerHTML = "元素3被选中。<br/>";
      }
    }
  </script>

The above is the JavaScript code to be executed when the selected state of the radio button changes. You can use the checked attribute to get the selected status of a radio button. True if the radio button is checked, false if not. Make sure the attribute is checked and the message is displayed as HTML for the element with the "output" ID.

 <form name="form1" action="">
    <input id="Checkbox1" type="checkbox" /><label for="Checkbox1">单选项目1</label><br />
    <input id="Checkbox2" type="checkbox" /><label for="Checkbox2">单选项目2</label><br />
    <input type="button" value="Exec" onclick="onButtonClick();" />
  </form>

The above is the HTML of the form part. The form has two checkboxes and a button. Execute the onBVuttonCLick() function on the button's onclick event.

Run results

Execute the above HTML file. The effect shown below will be displayed.

How to get the selected state of a radio button using JavaScript

Click the radio button to select it. When selected, a message appears at the bottom of the radio button indicating that the element has been selected.

How to get the selected state of a radio button using JavaScript

In the case of using GetElementById

Using DOM, you can get the selection status of the radio button in GetElemenById, using GetElementById, You can get the radio button even if it doesn't exist in the form.

The code is as follows

<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
  <title></title>
  <script type="text/javascript" language="javascript">
    function onHow to get the selected state of a radio button using JavaScriptChange() {
      radiobtn1 = document.getElementById("Radio1");
      radiobtn2 = document.getElementById("Radio2");
      radiobtn3 = document.getElementById("Radio3");

      target = document.getElementById("output");

      if (radiobtn1.checked == true) {
        target.innerHTML = "元素1被选中。<br/>";
      }
      else if (radiobtn2.checked == true) {
        target.innerHTML = "元素2被选中。<br/>";
      }
      else if (radiobtn3.checked == true) {
        target.innerHTML = "元素3被选中。<br/>";
      }
    }
  </script>

</head>
<body>
  <input id="Radio1" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" /><label for="Radio1">How to get the selected state of a radio button using JavaScript 元素1</label><br/>
  <input id="Radio2" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" /><label for="Radio2">How to get the selected state of a radio button using JavaScript 元素2</label><br />
  <input id="Radio3" name="RadioGroup1" type="radio" onchange="onHow to get the selected state of a radio button using JavaScriptChange();" /><label for="Radio3">How to get the selected state of a radio button using JavaScript 元素3</label><br />
  <div id="output"></div>
</body>
</html>

Instructions:

When a radio button is clicked and the selection state is changed, the onHow to get the selected state of a radio button using JavaScriptChange() function will be called. Inside the function, call the GetElementById method and get the radio button objects for Radio 1, Radio 2, Radio 3. The selection state is determined by the value of the checked property of the radio button object. A message corresponding to the selected state of the radio button appears on the page.

Run results

Use a web browser to execute the above HTML file. The effect shown below will be displayed.

How to get the selected state of a radio button using JavaScript

Click the radio button to select. When selected, the selected message will be displayed.

How to get the selected state of a radio button using JavaScript

#If you change the radio button to select, the message content will change accordingly.

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