JS：输入用户名并打印出来

Question

我是JS的初学者。我尝试从 HTML 表单获取输入。并从函数中打印出单词。我读过W3中的JS。但是，它总是出错。谁能帮帮我。

HTML - 关于表格

<form method="get">
<h2>Please leave your contact information for us</h2>

<label for="FirstName">First Name:</label>
<input type="text" id="FirstName" name="firstName" placeholder="Your First Name"><br>

<label for="LastName">Last Name:</label>
<input type="text" id="LastName" name="LastName" placeholder="Your last Name"><br>

<label for="email">E-mail:</label>
<input type="e-mail" id="email" name="eMail"><br>


<label for="password">Password:</label>
<input type="password" id="password" name="passWord"><br>

<label for="suGession">sub gesstion:</label><br>
<textarea name="suggestion" id="suGession" cols="30" rows="10"></textarea>
<br>
<br>
<p>What do you usually cook?</p>
<input type="text">
<button type="submit" onclick="welcome()">Give Us Help</button>

</form>

我的JS代码

var first = document.getElementById("FirstName");
var last = document.getElementById("LastName");     

function welcome(){

    var welcomeF = "Welcome" + first +" "+ last;
    return welcomeF;

}

console.log(welcome());

Answer 1

您需要更改：

var welcomeF = "Welcome" + first +" "+ last;

至：

var welcomeF = "Welcome" + first.value +" "+ last.value;

first 和 last 只是对 dom 节点的引用，而不是其中的值

Answer 2

使用 first.value 获取元素的值并使用 onSubmit 属性而不是使用 onclick。

看看这段代码，我对你的代码做了一些修改。

Javascript :

    function welcome(){
    var first = document.getElementById("FirstName").value; 
    var last = document.getElementById("LastName").value;
    var welcomeF = "Welcome " + first +" "+ last;
    console.log(welcomeF);
    window.alert(welcomeF);
    return false; //To prevent it from going into next page.
}

Html :

    <form  onSubmit = "return welcome();">
    <h2>Please leave your contact information for us</h2>

    <label for="FirstName">First Name:</label>
    <input type="text" id="FirstName" name="firstName" placeholder="Your First Name"><br>

    <label for="LastName">Last Name:</label>
    <input type="text" id="LastName" name="LastName" placeholder="Your last Name"><br>

    <label for="email">E-mail:</label>
    <input type="e-mail" id="email" name="eMail"><br>


    <label for="password">Password:</label>
    <input type="password" id="password" name="passWord"><br>

    <label for="suGession">sub gesstion:</label><br>
    <textarea name="suggestion" id="suGession" cols="30" rows="10"></textarea><br><br>
    <p>What do you usually cook?</p>
    <input type="text">
    <button type="submit" >Give Us Help</button>

JS：输入用户名并打印出来

JS: Input user name and print it out

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