javascript - javascript没有获得价值

Question

我想知道以下内容为什么会给我带来麻烦，它看起来很简单，但我不确定发生了什么。

所以我有一个输入框，我希望用户填写它，每次我运行以下

我身份不明，我不知道为什么。

<input type="numbers" name="price" class="sell" placeholder="$0.00">

我正在使用以下 javascript

var price = document.getElementsByName("price")
    alert(price.value);

Answer 1

var price = document.getElementsByName("price")[0];
    alert(price.value);

document.getElementsByName will give you HTMLCollection (kind of array) as a return type. This is because a number of elements in your dom may share the same name. So if you have number of checkboxes having same name you can refere each checkbox with the array index.

Answer 2

You have several problems.

The one causing your problem is that getElementsByName returns an HTMLCollection (which is like an array), not a single element. You need to pull the first item off it before trying to access its properties.

var price = document.getElementsByName("price")[0];

Second, numbers it not a type of input. number (singular) is.

Third, if you give the example $0.00 then you are informing people that you expect them to type a value starting with a $ sign. You can't have a $ sign in a number.