regexp以匹配序列（如果不是以特定字符开头和结尾）

Question

When it comes to regexps, I'm not very good at finding one that works and suits my needs.I need to match a word say foo if it is not included between a character say [ and another character say ]

 "[foo] foo" // I need to replace foo with bar
 // expected result : "[foo] bar" but not "[bar] bar"

I know how to match it if it is not followed by ]

 "foo] foo".replace(/foo(!?\])/g,"bar")

And I also know how to match it if it is not preceded by [

 " [foo foo".replace(/(\[)?foo/g,function(_0,_1) {
      return _1:_0?"bar"
 })

But I don't know how to put them together.Thank you!

Answer 1

请尝试使用此词来匹配[和]之间的单词

"[foo] foo".match(/\[.*?\]/g)

Answer 2

You need the following regex:

(?<!\[)foo(?!])

it has negative lookbehind for [ and negative lookahead for ] .

Answer 3

Using a negative lookahead you can use this regex:

var repl = str.replace(/\bfoo\b(?![^\]\[]*\])/g, 'bar');

RegEx Demo

(?![^\\]\\[]*\\]) is a negative lookahead assertion. This asserts failure when it finds a ] without matching [ or ] on the way, thus not matching foo inside [...] .

\\b is used for word boundary.