Javascript使用正则表达式替换非捕获组

Question

我正在尝试删除日期字符串中的序数.

我需要验证序数之前至少有一个数字,这样我们就知道它是序数而不是单词的一部分.这是正确的正则表达式:

/(?:\d)(st|nd|rd|th)/g

现在,当我在Javascript中对字符串进行正则表达式替换时,我最终替换了非捕获组"捕获"序数之前的前导数字,您可以在此处看到:

var inpt;

function swapText()
{
  var str = inpt.value;
  var reg = /(?:\d)(st|nd|rd|th)/g;

  str = str.replace(reg, "");
  
  inpt.value = str;
}

function init()
{
  inpt = document.getElementById('str_data');
  var btn = document.getElementById('swap_btn');
  btn.addEventListener('click', swapText, false);
}

setTimeout(init, 0);

body {
  font:13.23px "Open Sans", Verdana, sans-serif;
}

input {
  min-height:30px;
  height:auto;
  width:auto;
  padding: 6px 8px;
  color: #424242;
}

.btn {
	display: inline-block;
	padding: 8px 12px;
	margin-bottom: 0;
	font-size: 14px;
	font-weight: 500;
	line-height: 1.428571429;
	text-align: center;
	white-space: nowrap;
	vertical-align: middle;
	cursor: pointer;
	border: 1px solid transparent;
	border-radius: 4px;
	-webkit-user-select: none;
	-moz-user-select: none;
	-ms-user-select: none;
	-o-user-select: none;
	user-select: none;
}

.btn-success {
	color: #fff;
	background-color: #5cb85c;
	border-color: #4cae4c;
}

.btn-primary {
    color: #fff;
    background-color: #337ab7;
    border-color: #2e6da4;
}

input, button, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

button, html input[type="button"], input[type="reset"], input[type="submit"] {
  cursor: pointer;
  -webkit-appearance: button;
}

button, select {
  text-transform: none;
}

<input id="str_data" value="The 1st, 2nd, 3rd, and 4th" />
<button id="swap_btn" class="btn btn-primary" >
  Swap Text
</button>

代码段不起作用？检查 这个JSFiddle.

现在,在探讨建议的匹配问题之后,我发现在某些语言中,在正则表达式匹配中忽略非捕获组.这是Javascript的情况吗？

例如,如果我有字符串,The 1st, 2nd, 3rd, and 4th并且我string.match使用上面提供的正则表达式运行a ,那么这将是我的输出:

var str = "The 1st, 2nd, 3rd, and 4th";
var opt = JSON.stringify(str.match(/(?:\d)(st|nd|rd|th)/g));
document.body.innerHTML = opt;

如您所见,我的非捕获组被忽略了.这是为什么我也string.replace忽略了我的捕获组？如果是这样,那么我应该如何替换日期字符串中的"序数"并验证Javascript中是否存在前导数字(当然还有前导数字)？谢谢!

更新:这是一个与已接受的正则表达式的片段

var inpt;

function swapText()
{
  var str = inpt.value;
  var reg = /(\d)(?:st|nd|rd|th)/g;

  str = str.replace(reg, "$1");
  
  inpt.value = str;
}

function init()
{
  inpt = document.getElementById('str_data');
  var btn = document.getElementById('swap_btn');
  btn.addEventListener('click', swapText, false);
}

setTimeout(init, 0);

body {
  font:13.23px "Open Sans", Verdana, sans-serif;
}

input {
  min-height:30px;
  height:auto;
  width:auto;
  padding: 6px 8px;
  color: #424242;
}

.btn {
	display: inline-block;
	padding: 8px 12px;
	margin-bottom: 0;
	font-size: 14px;
	font-weight: 500;
	line-height: 1.428571429;
	text-align: center;
	white-space: nowrap;
	vertical-align: middle;
	cursor: pointer;
	border: 1px solid transparent;
	border-radius: 4px;
	-webkit-user-select: none;
	-moz-user-select: none;
	-ms-user-select: none;
	-o-user-select: none;
	user-select: none;
}

.btn-success {
	color: #fff;
	background-color: #5cb85c;
	border-color: #4cae4c;
}

.btn-primary {
    color: #fff;
    background-color: #337ab7;
    border-color: #2e6da4;
}

input, button, select, textarea {
  font-family: inherit;
  font-size: inherit;
  line-height: inherit;
}

button, html input[type="button"], input[type="reset"], input[type="submit"] {
  cursor: pointer;
  -webkit-appearance: button;
}

button, select {
  text-transform: none;
}

<input id="str_data" value="The 1st, 2nd, 3rd, and 4th" />
<button id="swap_btn" class="btn btn-primary" >
  Swap Text
</button>

Answer 1

使用捕获组并替换为$1.use replace而不是match.

(\d)(?:st|nd|rd|th)

见演示.

https://regex101.com/r/iJ7bT6/6

var re = /(\d)(?:st|nd|rd|th)/g; 
var str = 'The 1st, 2nd, 3rd, and 4th';
var subst = '$1'; 

var result = str.replace(re, subst);