Split a camelCase string with regex

Question

I have a Camel case string like this s = 'ThisIsASampleString' and I want to split into an array using the capital letters as the delimiting point. I am expecting this:

['This', 'Is', 'A', 'Sample', 'String']

Here is what I have done so far

s = "ThisIsASampleString";
var regex = new RegExp('[A-Z]',"g");
var arr = s.split(re);

But this is not giving me the correct result because it removes the matched character. I am getting this array as my result ["his", "s", "", "tring"]. It has removed all the matched capital letters.

How should I avoid this behavior and keep the matched characters also in my result array?

Answer 1

Your regex would split based on the uppercase but the result array doesn't include the matched value. Instead use positive look-ahead assertion to assert the position.

s = "ThisIsASampleString";
var arr = s.split(/(?=[A-Z])/);

console.log(arr);

Regex explanation here

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Or you can use String#match method instead.

s = "ThisIsASampleString";
var arr = s.match(/[A-Z][^A-Z]*/g);

console.log(arr);

Regex explanation here