Question

我试图检查文本框中键入的击键是否为数字。无论我输入的是什么，都会给我提供相同的警报窗口。它说＆＃34;你输入的数字不是数字＆＃34;。我似乎无法找到它为什么这样做。

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Part 1</title>
<script>
function Numcheck(){
    var number = Number(document.getElementById("enteredChar").value)
try{
if ("number" == "") throw "was empty"
if (isNaN("number")) throw "is not a number"
if (isFinite("number")) throw "is good."
}
catch(err){
alert("The number you entered " + err);
}
}
</script>
</head>

<body>
<form action="">
<input type="text" id="enteredChar" onkeypress="Numcheck()"/>
</form>
</body>
</html>

Answer 1

if (isNaN("number")) throw "is not a number"

您传入isNaN函数的值是"number"，实际上是字符串而不是数字。

您应该将所有"number"更改为number，这是变量的名称。

示例：

<script>
function Numcheck() {
    var number = Number(document.getElementById("enteredChar").value)

    try {
        //This if is not required. number will never be an empty string. 
        //It will be either a valid number, or NaN.
        //if (number == "") throw "was empty";
        if (isNaN(number)) throw "is not a number";
        if (isFinite(number)) throw "is good.";
    }
    catch(err) {
        alert("The number you entered " + err);
    }
}
</script>

尝试Catch块只给出我的一个投掷响应

1 个答案: