如何使用正则表达式 javascript 将大写更改为小写
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how to change uppercase to lowercase with regex javascript
提问by John Smith
It could be any string, it should match only the UPPERCASE part and change to lowercase, for example:
它可以是任何字符串，它应该只匹配大写部分并更改为小写，例如：
"It's around August AND THEN I get an email"
"It's around August AND THEN I get an email"
become
变得
"It's around August and then I get an email"
"It's around August and then I get an email"
as you can see the word It's, Augustand Ishould be ignored
你可以看到这个词It's，August并且I应该被忽略
回答by Sam
Use /\b[A-Z]{2,}\b/gto match all-caps words and then .replace()with a callback that lowercases matches.
使用/\b[A-Z]{2,}\b/g以匹配所有大写的单词，然后.replace()用一个回调小写字母匹配。
var string = "It's around August AND THEN I get an email",
regex = /\b[A-Z]{2,}\b/g;
var modified = string.replace(regex, function(match) {
return match.toLowerCase();
});
console.log(modified);
// It's around August and then I get an emailAlso, feel free to use a more complicated expression. This one will look for capitalized words with 1+ length with "I" as the exception (I also made one that looked at the first word of a sentence different, but that was more complicated and requires updated logic in the callback function since you still want the first letter capitalized):
另外，请随意使用更复杂的表达式。这个将查找长度为 1+ 的大写单词，“I”作为例外（我还制作了一个查看句子的第一个单词的不同单词，但这更复杂，并且需要在回调函数中更新逻辑，因为您仍然希望第一个字母大写）：
\b(?!I\b)[A-Z]+\b
回答by baao
A solution without regex:
没有正则表达式的解决方案：
function isUpperCase(str) {
return str === str.toUpperCase();
}
var str = "It's around August AND THEN I get an email";
var matched = str.split(' ').map(function(val){
if (isUpperCase(val) && val.length>1) {
return val.toLowerCase();
}
return val;
});
console.log(matched.join(' '));