javascript regex skip square brackets

Question

I have a string

var oldName = "questions[0].answers[3].answer";

I want to increment the the answers part to [4]( +1 of what the current value is). If it is questions[0].answers[6].answer it should become questions[0].answers[7].answer.

I tried with the following but I am not getting any result.

var matches = oldName.match(/(\d+)answers(\d+)/)
var number1 = Number(matches[1]);
var number2 = Number(matches[2]);

I need to store the numbers in the string in 2 separate variables.

Answer 1

It is simple to do this, just supply a replacement function to String.replace :

str.replace(/answers\[(\d+)\]/, function (_, $1) {
     return "answers[" + (+$1 + 1) + "]";
});

(If you want an explanation on the parameters to the replacement function, you can read the MDN link above, or my answer here )

But whether this is a good solution to the bigger problem, I don't know.