如何在javascript中反转字符串？
[英]How to reverse a string in javascript?
问题描述
I'm trying to learn JavaScript through.html files in Visual Studio 2013.
我正在尝试通过 Visual Studio 2013 中的 .html 文件学习 JavaScript。
I know there are easier ways to reverse a string in JavaScript, but my main aim is to understand interaction between html and JavaScript to provide such a solution.我知道有更简单的方法可以在 JavaScript 中反转字符串，但我的主要目的是了解 html 和 JavaScript 之间的交互以提供这样的解决方案。
Also, the IDE has to be Visual Studio as eventually I want to code this same logic using.aspx files.此外，IDE 必须是 Visual Studio，因为最终我想使用 .aspx 文件编写相同的逻辑。
So, for my initial learning attempt, I'm trying to implement the following logic:因此，对于我最初的学习尝试，我试图实现以下逻辑：
- get a string from input tag of form,从表单的输入标签中获取一个字符串，
- submit form resulting in the script submit() to run,提交表单导致脚本submit()运行，
- the script reverses the string, and then脚本反转字符串，然后
- displays reversed string in the same input tag which is now disabled在现在已禁用的同一输入标签中显示反转字符串
Code I've written is as follows:我写的代码如下：
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
<head>
<script type="text/javascript">
function reverseString() {
var s = document.getElementById('reverseString').value;
var reversed;
for (var i = s.length - 1; i >= 0; i--) {
reversed += s[i];
}
document.getElementById('reverseString').disabled = true;
document.getElementById('reverseString').value = reversed;
}
function submit(form) {
reverseString();
}
</script>
<title>Play with Code</title>
</head>
<body>
<form name="myform" onsubmit="submit();">
Reverse String: <input type="text" id="reverseString"/><br/>
<input type="submit" value="Submit"/>
</form>
</body>
</html>
It doesn't work and I'm really clueless as to how to solve it.它不起作用，我真的不知道如何解决它。
I unsuccessfully tried to debug following the instructions provided by these links:我尝试按照这些链接提供的说明进行调试但未成功：
How to debug (only) JavaScript in Visual Studio? 如何在 Visual Studio 中调试（仅）JavaScript？
http://www.aspsnippets.com/Articles/Debug-JavaScript-and-jQuery-using-Visual-Studio-in-Internet-Explorer-browser.aspx http://www.aspsnippets.com/Articles/Debug-JavaScript-and-jQuery-using-Visual-Studio-in-Internet-Explorer-browser.aspx
Please help me to fix this code and also, if possible, please advise or direct me on how to debug such a piece of code.请帮我修复这段代码，如果可能的话，请建议或指导我如何调试这样一段代码。
Thanks.谢谢。
3 个解决方案
解决方案1
1 已采纳 2015-09-17 08:41:14
Here's a working code with comments to explain you what you are doing wrong:这是一个带有注释的工作代码，可以解释您做错了什么：
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
<head>
<title>Play with Code</title>
</head>
<body>
<form name="myform" id="form">
Reverse String: <input type="text" id="reverseString"/><br/>
<input type="submit" value="Submit"/>
</form>
<script>
function reverseString() {
var s = document.getElementById('reverseString').value;
// reverse should initialized as a empty String
// to prevent adding char to "undefined" string
var reversed = '';
for (var i = s.length - 1; i >= 0; i--) {
reversed += s[i];
}
document.getElementById('reverseString').disabled = true;
document.getElementById('reverseString').value = reversed;
}
function submit(ev) {
// preventDefault prevent the form to do his automatic
// behavior which submit the form with a new HTTP request
ev.preventDefault();
reverseString();
}
// Attach the event to the form
document.getElementById('form').addEventListener('submit', submit);
</script>
</body>
</html>
解决方案2
0 2015-09-17 09:00:43
More Info on Debugging 有关调试的更多信息
//HTML
Reverse String: <input type="text" id="reverseString"/><br/>
<input type="button" value="Submit" onClick="funcreverse()"/>
//Script
function funcreverse () {
var s = document.getElementById('reverseString').value;
var reversed = '';
for (var i = s.length - 1; i >= 0; i--) {
reversed += s[i];
}
document.getElementById('reverseString').disabled = true;
document.getElementById('reverseString').value = reversed;
};
解决方案3
0 2022-12-22 05:31:48
"use strict";
function reverseString(str) {
let rev = "";
let len = str.length;
for (let i = len - 1; i >= 0; i--) {
rev += str[i];
}
return rev;
}
console.log(reverseString("Reverse"));
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