https://www.codewars.com/kata/5277c8a221e209d3f6000b56/train/javascript

validBraces.js

function validBraces(braces){
  if (braces.length < 2) return false
  var open = new Set(["{", "(", "["])
  var match = (a, b) => {
    if (a == '{' && b == '}') return true
    if (a == '[' && b == ']') return true
    if (a == '(' && b == ')') return true
    return false
  }
  var stack_open = []
  var i = 0
  while (i < braces.length) {
    var b = braces[i]
    if (open.has(b)) {
      stack_open.push(b)
    } else {
      if (!match(stack_open.pop(), b)) return false
    }
    i++
  }
  return stack_open.length == 0
}

Write a function that takes a string of braces, and determines if the order of the braces is valid. It should return true if the string is valid, and false if it's invalid.

This Kata is similar to the Valid Parentheses Kata, but introduces new characters: brackets [], and curly braces {}. Thanks to @arnedag for the idea!

All input strings will be nonempty, and will only consist of parentheses, brackets and curly braces: ()[]{}.