How do I insert something at a specific character with Regex in Javascript

Question

I have string "foo?bar" and I want to insert "baz" at the ?. This ? may not always be at the 3 index, so I always want to insert something string at this ? char to get "foo?bazbar"

Answer 1

The String.protype.replace method is perfect for this.

Example

let result = "foo?bar".replace(/\?/, '?baz');
alert(result);

I have used a RegEx in this example as requested, although you could do it without RegEx too.

Additional notes.

1. If you expect the string "foo?bar?boo" to result in "foo?bazbar?boo" the above code works as-is
2. If you expect the string "foo?bar?boo" to result in "foo?bazbar?bazboo" you can change the call to .replace(/\?/g, '?baz')

Answer 2

You don't need a regular expression, since you're not matching a pattern, just ordinary string replacement.

string = 'foo?bar';
newString = string.replace('?', '?baz');
console.log(newString);