TypeError : map is not a function

Question

I've a simple problem,

Given a string S of '(' and ')' parentheses, we add the minimum number of parentheses ( '(' or ')', and in any positions ) so that the resulting parentheses string is valid.

Formally, a parentheses string is valid if and only if: It is the empty string, or It can be written as AB (A concatenated with B), where A and B are valid strings, or It can be written as (A), where A is a valid string. Given a parentheses string, return the minimum number of parentheses we must add to make the resulting string valid.

This is my solution in JS,

const minAddToMakeValid = S => {
    const stack = [];
    let count = 0;
    S.map(c => {
        if(c === '('){
            stack.push(c);
        }
        else if(c === ')' && stack[stack.length -1] === '('){
            stack.pop();
        }
        else{
            count ++;
        }
    });
    return count + stack.length;

};
const S = "())";
console.log(minAddToMakeValid(S));

I get the following error,

TypeError: S.map is not a function
    at minAddToMakeValid (/Users/melissa/Dropbox/js/leetcode-js/bin/921_minAddToMakeParanthesisValid.js:4:7)
    at Object.<anonymous> (/Users/melissa/Dropbox/js/leetcode-js/bin/921_minAddToMakeParanthesisValid.js:19:13)
    at Module._compile (internal/modules/cjs/loader.js:721:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:732:10)
    at Module.load (internal/modules/cjs/loader.js:620:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:560:12)
    at Function.Module._load (internal/modules/cjs/loader.js:552:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:774:12)
    at executeUserCode (internal/bootstrap/node.js:342:17)
    at startExecution (internal/bootstrap/node.js:276:5)

Answer 1

A String is not an Array : it doesn't have the same methods.

However, you can use S.split("") to get an array and then map over it