为什么无法从输入框中获取输入? [英] Why can't I get the input from the input box?
本文介绍了为什么无法从输入框中获取输入?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我做了以下代码来从输入框中获取输入.但是,它无法获得输入吗?为什么?
I have made the following code to get the input from the input box. However, it can't get the input? Why?
var p = document.getElementById("paragraph");
var input = document.getElementById("input").value;
var foodname;
function changeP() {
alert(input);
if (input === "abc") {
foodname = "Hey Yo!";
} else if (input === "def") {
foodname = "!oY yeH";
} else {
foodname = "N/A";
}
p.innerText = foodname;
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Input Detecting</title>
</head>
<body>
<p id="paragraph">Please type in the code in the following input bar. </p>
<input id="input">
<button onClick="changeP()">Confirm</button>
<script src="JavaScript.js"></script>
</body>
</html>
我希望当我键入 abc
时,警报会是嘿!
,但它什么也不会输出.
I expect the alert will be Hey Yo!
when I type abc
but it outputs nothing.
推荐答案
因为每次运行函数 changeP()
时,都必须获取输入 value
.
现在,您将在页面加载时获取该值,因此该值始终为 null
Because you have to get the input value
, each time you run the function changeP()
.
Now, you are getting the value when the page loads, so the value is always null
//This is JavaScript.js
function changeP() {
var p = document.getElementById("paragraph");
var input = document.getElementById("input").value;
var foodname;
alert(input);
if (input === "abc") {
foodname = "Hey Yo!";
} else if (input === "def") {
foodname = "!oY yeH";
} else {
foodname = "N/A";
}
p.innerText = foodname;
}
这篇关于为什么无法从输入框中获取输入?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文