JavaScript中带有正则表达式的意外结果

Question

This is my String.

 var re = "i have a string";

And this my expression

var str = re.replace(/(^[a-z])/g, function(x){return x.toUpperCase();});

I want that it will make the the first character of any word to Uppercase. But the replacement above return only the first character uppercased. But I have added /g at the last.

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Where is my problem?

Answer 1

You can use the \\b to mark a boundary to the expression.

 const re = 'i am a string'; console.log(re.replace(/(\\b[az])/g, (x) => x.toUpperCase())); 

The metacharacter \\b is an anchor like the caret and the dollar sign. It matches at a position that is called a "word boundary". This match is zero-length.

There are three different positions that qualify as word boundaries:

1. Before the first character in the string, if the first character is a word character.
2. After the last character in the string, if the last character is a word character.
3. Between two characters in the string, where one is a word character and the other is not a word character.

Answer 2

Vlaz的评论对我来说似乎是正确的答案-通过在样式的开头加上“ ^”，可以确保只找到第一个字符-尽管“ / g”，因为它们没有立即跟随行的开头。