How to search strings with brackets using Regular expressions

Question

I have a case wherein I want to search for all Hello (World) in an array. Hello (World) is coming from a variable and can change. I want to achieve this using RegExp and not indexOf or includes methods.

testArray = ['Hello (World', 'Hello (World)', 'hello (worlD)']

My match should return index 1 & 2 as answers.

Answer 1

Use the RegExp constructor after escaping the string (algorithm from this answer), and use some array methods:

const testArray = ['Hello (World', 'Hello (World)', 'hello (worlD)'];
const string = "Hello (World)".replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
const regex = new RegExp(string, "i");
const indexes = testArray.map((e, i) => e.match(regex) == null ? null : i).filter(e => e != null);
console.log(indexes);

Answer 2

This expression might help you to do so:

(\w+)\s\((\w+)

You may not need to bound it from left and right, since your input strings are well structured. You might just focus on your desired capturing groups, which I have assumed, each one is a single word, which you can simply modify that.

With a simple string replace you can match and capture both of them.

RegEx Descriptive Graph

This graph shows how the expression would work and you can visualize other expressions in this link:

Performance Test

This JavaScript snippet shows the performance of that expression using a simple 1-million times for loop.

repeat = 1000000;
start = Date.now();

for (var i = repeat; i >= 0; i--) {
 var string = "Hello (World";
 var regex = /(\w+)\s\((\w+)/g;
 var match = string.replace(regex, "$1 & $2");
}

end = Date.now() - start;
console.log("YAAAY! \"" + match + "\" is a match  ");
console.log(end / 1000 + " is the runtime of " + repeat + " times benchmark test.  ");

Answer 3

testArray = ['Hello (World', 'Hello (World)', 'hello (worlD)'];
let indexes = [];
testArray.map((word,i)=>{
  if(word.match(/\(.*\)/)){
    indexes.push(i);
  }
});
console.log(indexes);