正则表达式只有在没有跟随另一个字符的情况下才匹配一个字符，然后只替换该初始字符

For instance,

(/=[^>]/, '═')

I'd like to keep that match, but only replace the equals sign with the double-horizontal-line. As it is, it matches any '=' that is followed by anything that isn't a '>' but then replaces both the '=' and the following character with the replacing character, I want to keep the following character, but replace just the '='. This is in ruby, if it makes any syntactic difference.I'd like to k