正则表达式更改字符串中的某些单词

Question

I am trying to get my head around regular expressions. I thought the following would work, but unfortunately it isn't.

What I want to do:

Given a string str (see below) I want to replace any word that is not shade or gravel with the word gravel .

str = "gravel shade water grass people water shade";
output = str.replace(/([^gravel|^shade])/g,' gravel ');  

output should equal gravel shade gravel gravel gravel gravel shade . What I have is close enough but a bit off.

Answer 1

Your ([^gravel|^shade]) matches and captures into Group 1 any one single character that is not g , r , a , v , e , l , | , ^ , and replace all of them with gravel .

You can use

/\b(?!(?:shade|gravel)\b)\w+\b/g

See the regex demo

Pattern description:

• \\b - leading word boundary
• (?!(?:shade|gravel)\\b) - a negative lookahead that will exclude matching whole words shade and gravel
• \\w+ - 1+ word characters (belonging to the [A-Za-z0-9_] set)
• \\b - trailing word boundary.

 var str = 'gravel shade water grass people water shade'; var result = str.replace(/\\b(?!(?:shade|gravel)\\b)\\w+\\b/g, 'gravel'); document.body.innerHTML = result; 

Answer 2

Here is a non-regex solution for your problem using split/join and array.map :

 var str = "gravel shade water grass people water shade"; var repl = str.split(' ').map(function (w) { return (w!='gravel' && w!= 'shade')?'gravel':w; }).join(' ') document.writeln("<pre>" + repl + "</pre>") //=> "gravel shade gravel gravel gravel gravel shade"