问候，我有这个输入字段， <input name="question"/>我想在单击提交按钮时调用IsEmpty函数。我尝试了下面的代码，但是没有用。有什么建议吗？<html><head> <title></title> <meta http-equiv="Content-Type" content="text/html; charset=unicode" /> <meta content="CoffeeCup HTML Editor (www.coffeecup.com)" name="generator" /></head><body> <script language="Javascript"> function IsEmpty() { if (document.form.question.value == "") { alert("empty"); } return; } </script> Question: <input name="question" /> <br/> <input id="insert" onclick="IsEmpty();" type="submit" value="Add Question" /></body></html>
3 回答
慕桂英4014372
TA贡献1871条经验 获得超13个赞
<script type="text/javascript">
function validateForm() {
var a = document.forms["Form"]["answer_a"].value;
var b = document.forms["Form"]["answer_b"].value;
var c = document.forms["Form"]["answer_c"].value;
var d = document.forms["Form"]["answer_d"].value;
if (a == null || a == "", b == null || b == "", c == null || c == "", d == null || d == "") {
alert("Please Fill All Required Field");
return false;
}
}
</script>
<form method="post" name="Form" onsubmit="return validateForm()" action="">
<textarea cols="30" rows="2" name="answer_a" id="a"></textarea>
<textarea cols="30" rows="2" name="answer_b" id="b"></textarea>
<textarea cols="30" rows="2" name="answer_c" id="c"></textarea>
<textarea cols="30" rows="2" name="answer_d" id="d"></textarea>
</form>
慕村9548890
TA贡献1884条经验 获得超4个赞
您缺少必填<form>元素。您的代码应如下所示：
function IsEmpty() {
if (document.forms['frm'].question.value === "") {
alert("empty");
return false;
}
return true;
}
<form name="frm">
Question: <input name="question" /> <br />
<input id="insert" onclick="return IsEmpty();" type="submit" value="Add Question" />
</form>
蓝山帝景
TA贡献1843条经验 获得超7个赞
输入字段可以包含空格，您要防止这种情况：
function isEmpty(str){
return !str.replace(/\s+/, '').length;
}
例：
function isEmpty(str){
return !str.replace(/\s+/, '').length;
}
document.getElementById("name").addEventListener("input", function() {
if( isEmpty(this.value) ) {
console.log( "NAME IS EMPTY!" )
}
});
<input id="name" type="text">
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