JS: Input user name and print it out

问题

I'm the beginner of JS. I try to get input from the HTML form. And print words out from function. I have read JS in W3. However, it keeps going wrong. Could somebody give me a hand.

HTML - about the form

<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>

My JS code

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

function welcome(){

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

}

console.log(welcome());

回答1:

Use first.value to get the value of the element & use onSubmit attribute in instead of using onclick.

Have a look at this code, I did some changes in your code.

Javacript :

    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>

回答2:

You need to change:

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

to:

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

first and last are just references to the dom nodes, not the value in them

来源：https://stackoverflow.com/questions/31195709/js-input-user-name-and-print-it-out

标签

javascript

getelementbyid

input-field