If-statement executes everything but return-statement-CodePudding

I'm trying to understand how stacks are working through code. Now, I tried to write a simple bracket-matching program: I've wrote linked list implementation and I've used it to implement stack in JS. The idea is in iterating through all characters in string and putting open-brackets in stack. After this, if there is no matching bracket for the top-bracket, function should return false. The main problem is, that if-statement executes everything but return-statement in it.

Input: ([(a()]])

Desired output: false

function isBalanced(string) {
  let stack = new Stack();
  [...string].forEach(char => {
    let bracket
    if (char === '[' || char === '(') {
      stack.push(char)
    } else {
      if (stack.isEmpty()) {
        return false
      }

      bracket = stack.pop().data
      console.log(`PAIR: ${bracket}${char}`)
      if (!(bracket === "[" && char === "]") && !(bracket === "(" && char === ")")) {
        console.log("working")
        return false
      }
    }});

    return stack.isEmpty();
}

let string = '([(a()]])'

console.log(isBalanced(string))

I've used console.log() to check if my statement works and on which pairs does it work.

Output in console looks like this:

PAIR: (a
working
PAIR: ()
PAIR: []
PAIR: (]
working
true

As you can see, when statement is true, it's definitely work, but it doesn't call the inner return-statement (after first 'working' output, there should be no more pairs in console; just false). Where is the problem?

CodePudding user response：

You could use Array#every along with the length check of the stack and return inside of the callback for every right character true.

function isBalanced(string) {
    const
        closed = { '(': ')', '[': ']' },
        stack = [];
    return [...string].every(char => {
        if (char === '[' || char === '(') {
            stack.push(char);
            return true;
        }
        if (!stack.length) return false;
        const bracket = stack.pop();
        console.log(`PAIR: ${bracket}${char}`);
        return closed[bracket] === char;
    }) && !stack.length;
}

console.log(isBalanced('(([()]))'));
console.log(isBalanced('([(a()]])'));

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