为什么我无法从输入框中获取输入? [英] Why can't I get the input from the input box?
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问题描述
我做了以下代码来从输入框中获取输入.但是，它无法获取输入?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>我希望当我输入 abc 时警报会是 Hey Yo! 但它什么都不输出.
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changeP()函数时，都要得到输入的value.
现在，您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;
}
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