Javascript：在特定位置替换字符串

Question

I have a String like that :

var str = "Hello, it is a <test>12345</test> and it's fun";

I would like to replace "12345" by "****".

The script must take into account the fact that the string containing between and is never the same.

Answer 1

You can use this regex:

str = str.replace(/(<test>).*?(?=<\/test>)/, '$1*****');
//=> "Hello, it is a <test>*****</test> and it's fun"

If you don't want lookahead then use capturing groups on both sides:

str = str.replace(/(<test>).*?(<\/test>)/, '$1*****$2');
//=> "Hello, it is a <test>*****</test> and it's fun"

Answer 2

If digits won't always be wrapped between a <test> tag, here's another way to solve the same problem.

var str = "Hello, it is a <test>12345</test> and it's fun";

var numberPattern = /(\<\w+\>)(\d+)(\<\/\w+\>)/gi;

str = str.replace(numberPattern, "$1****$3");

// str is now "Hello, it is a <test>****</test> and it's fun"