如何在JavaScript之后大写首字母，问号和感叹号？ [英] How to capitalize first letter after period, question mark and exclamation in JavaScript?

问题描述

我有一个textarea，我希望每个句子中的每个首字母大写。

I have a textarea, where I want every first letter in each sentence to be capitalized.

现在我有这个：

evt.target.value = evt.target.value.replace(/.+?[\.\?\!](\s|$)/g, function(a) {
    return a.charAt(0).toUpperCase() + a.slice(1);
});

这是af函数，其中 evt.target 是textarea，函数在keyup上调用。

And this goes in af function, where evt.target is the textarea, and the function is called on keyup.

它很好用，除了它没有立即大写。
如果我写：

It works great, except that it doesn't capitalize instantly. If I write:

嘿。我需要一些正则表达式。

Hey. i need some regular expression for this.

然后只有当我在这个结尾处放置一个句点时，I才会大写。如果它出现在。> whitespace<之后，我希望它在输入后立即大写I。或！> whitespace<或者？> whitespace<。

then the "I" will capitalize only when i put a period at the end of "this". I would like it to capitalize the "I" instantly after typing it, if it comes after an ". >whitespace<" or "! >whitespace<" or "? >whitespace<".

我尝试使用谷歌搜索很多东西，但不幸的是，这个正则表达式的东西对我来说太复杂了。有没有人可以正确地写这个，快速解释一下？

I tried googling a lot of stuff, but unfortunately, this regex stuff is too complicated for me. Could anyone write this correctly, with a quick explanation?

推荐答案

我迟到了，但也许有人需要jQuery代码。
也适用于第一句话。

I'm late, but maybe somebody needs jQuery code for it. That works for first sentence too.

$('input').on('input', function (evt) {
    var $this = $(evt.target),
        re = /(^|[.!?]\s+)([a-z])/g,
        val = $this.val().replace(re, function (m, $1, $2) {
            return $1 + $2.toUpperCase();
        });
    $this.val(val);
});

https://jsfiddle.net/chukanov/oqg5o88u/1/

es6 update：

es6 update:

let re = /(^|[.!?]\s+)([a-z])/g;
$('input').on('input', function (evt) {
  let $this = $(this),
      val = $this.val().replace(re, (m, $1, $2) => $1 + $2.toUpperCase());
  $this.val(val);
});

https://jsfiddle.net/chukanov/oqg5o88u/27/

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