javascript - 使用 javascript 验证复选框

Question

我在验证多个复选框时遇到问题，我想检查用户是否至少选择了一个复选框。 我尝试使用 document.getElementByClassName 但不起作用

HTML:

<form id="formupload" method="post" enctype="multipart/form-data" action="upload.php" name="formupload">
    <input onKeydown="javascript:validateForm();" id="txtFileName" name="txtFileName" />
    <input onKeydown="javascript:validateForm();" id="title" name="title" />
    <input onKeydown="javascript:validateForm();" id="keywords" name="keywords" />
    <input onKeydown="javascript:validateForm();" id="description" name="description" />


        <span class="niche">
        <input type="checkbox" value="1" name="channel[]" class="css-checkbox" id="box_1">
        <label class="css-label" name="lbl_1" for="box_1">Amateur</label>
        </span>

        <span class="niche">
        <input type="checkbox" value="2" name="channel[]" class="css-checkbox" id="box_2">
        <label class="css-label" name="lbl_2" for="box_2">Amateur</label>
        </span>

        <span class="niche">
        <input type="checkbox" value="3" name="channel[]" class="css-checkbox" id="box_3">
        <label class="css-label" name="lbl_3" for="box_3">Amateur</label>
        </span>

<button id="btnSubmit" class="btn lbtn upBtn" type="submit">Upload</button>
</form>

这是 JavaScript:

function validateForm() {
    var txtFileName = document.getElementById("txtFileName");
    var titleTxt = document.getElementById("title");
    var tagsTxt = document.getElementById("keywords");
    var descTxt = document.getElementById("description");

    var isValid = true;
    if (txtFileName.value === "" || titleTxt.value === "" || tagsTxt.value === "" || descTxt.value === "" ) {
        isValid = false;
    }

    document.getElementById("btnSubmit").disabled = !isValid;

}

Answer 1

var checkBoxes=document.getElementsByClassName("css-checkbox");

var booleanResult=false;
for(var i=0;i<checkBoxes.length;i++){
 if(checkBoxes[i].checked){
    booleanResult=true;
    break;
 }
}
if(booleanResult==false){
alert("invalid")
}

<强> DEMO