[JavaScript] Brackets validator

brackets-validator.js

const assert = require('assert');

// '(', '{', '[' are called "openers."
// ')', '}', ']' are called "closers."

function validateBrackets(input) {
  const brackets = {
    openings: {
      '{': '}',
      '(': ')',
      '[': ']'
    },
    closing: {
      '}': '{',
      ')': '(',
      ']': '['
    }
  }
  const stack = [];
  for (const char of input) {
    // Opening
    if (brackets.openings[char]) {
      stack.push(char)
    } else if (brackets.closing[char]) {
      // Stack is empty
      if (stack.length === 0) return false;
      if (stack[stack.length - 1] === brackets.closing[char]) {
        stack.pop()
      } else {
        return false;
      }
    }
  }
  return stack.length === 0
}

assert.deepStrictEqual(validateBrackets('{[]}'), true)
assert.deepStrictEqual(validateBrackets('{[}'), false)