javascript对象不会在控制台中打印

Question

我有一个带有输入字段的表单。 我正在尝试在控制台中记录这些字段。 控制台显示“ createUser {firstName：null}”：对象

<div class="#">
    First Name:<br>
    <input placeholder="First Name" type="text" id="firstName" required> 
    <br>
</div>
<button onclick="user()" class="btn btn-primary">Sign Up</button>


function createUser(firstName, lastName, email, userName, password ){
    this.firstName = firstName;
}

function user(){
    var user = new createUser(document.getElementById(firstName.text));
    console.log(user);
}

console.log(user);

Answer 1

 var user = new createUser(document.getElementById('firstName').value);

这可能会有所帮助。

Answer 2

您要定义的对象名称与函数名称相同。 您需要更改一个或另一个。 您还需要获取输入字段的值。

尝试这个

var userObj = new createUser(document.getElementById('firstName').value);
console.log(userObj)

Answer 3

尝试这个

var user = '';
function createUser(firstName, lastName, email, userName, password ){
this.firstName = firstName;
}

function user(){
user = new createUser(document.getElementById(firstName).value);
//the same as accessing the text of <input value="this is my first name.">

console.log(user.firstName);
//log the property firstName of the object user. when you put this.firstName inside a function, it turns that into a property of of the variable you save it as. That means you must call it by using the variable and a "." and the property name ex firstName
}

console.log(user.firstName);

Answer 4

您可以通过以下方式在控制台日志中打印所有输入字段的值：

考虑到，您具有以下输入字段：

<div class="divclass">
    First Name:<br>
    <input placeholder="First Name" type="text" id="firstName" required> 
    <br>
    Middle Name:<br>
    <input placeholder="Middle Name" type="text" id="middleName" required> 
    <br>
    Last Name:<br>
    <input placeholder="Last Name" type="text" id="lastName" required> 
    <br>
</div>
<button onclick="user()" class="btn btn-primary">Sign Up</button>

function user(){
    var inputFields = document.querySelectorAll('#firstName, #middleName, #lastName');
    var inputFieldValues = Array.prototype.forEach.call(inputFields, function(inputField){
         console.log("id: "+inputFields.id + " value: "+inputField.value);
});

}