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How to compose JS functions with condition check at each step?

I have written my code

function takesst(str) {
  const str1 = [...str];
  const l = str1.length;
  const check = (str1) => (str1.indexOf('(') === 0 && str1.lastIndexOf(')') === l - 1);
  res = check(str1);
  return res;
}

The goal is to check that the first charachter is ( and the last ). Works OK.

node mycode.js
true

Now, the next step would be the high-order function that would include removing first and last character at each step and checking if the condition is met again.

const rec = f => f((...str).slice(1,-1))

String befor and after this step.

'(()())'
'()()'

How to do this?

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Answer

You could check for length and if the string starts and ends with wanted characters and the rest fullfills the same objective.

const check = string => !string.length || string.startsWith('(') && string.endsWith(')') && check(string.slice(1, -1));

console.log(check('((()))'));
console.log(check('((())'));
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