jstest tasks

checkBraces.js

/**
 * See demo (https://jsfiddle.net/yarkov_aleksei/e4Lwoq1g/)
 */

const braces = [['{', '}'], ['[', ']'], ['(', ')'], ['<', '>']]
const strBraces = braces.map(b => b.join('')).join('')

function isOpen(char) {
  for (let i = 0; i < braces.length; i++) {
    if (braces[i][0] === char) {
      return true
    }
  }
  return false
}

function matches(top, closed) {
  for (let i = 0; i < braces.length; i++) {
    if (braces[i][0] === top && braces[i][1] === closed) {
      return true
    }
  }
  return false
}

function checkBraces(str) {
  if (!str) {
    return 0
  }

  const expression = str.split('')
  let stack = []

  for (let i = 0; i < expression.length; i++) {
    if (strBraces.includes(expression[i])) {
      if (isOpen(expression[i])) {
        stack.push(expression[i])
      } else {
        if (stack.length === 0) {
          return 1
        }
        const top = stack.pop()
        if (!matches(top, expression[i])) {
          return 1
        }
      }
    }
  }

  return Number(!(stack.length === 0))
}

function test() {
  const data = [
    {
      Expression: '---(++++)----',
      Actual: checkBraces('---(++++)----'),
      Expected: 0
    },
    { Expression: '', Actual: checkBraces(''), Expected: 0 },
    {
      Expression: 'before ( middle []) after ',
      Actual: checkBraces('before ( middle []) after '),
      Expected: 0
    },
    { Expression: ') (', Actual: checkBraces(') ('), Expected: 1 },
    { Expression: '} {', Actual: checkBraces('} {'), Expected: 1 },
    { Expression: '<(   >)', Actual: checkBraces('<(   >)'), Expected: 1 },
    {
      Expression: '(  [  <>  ()  ]  <>  )',
      Actual: checkBraces('(  [  <>  ()  ]  <>  )'),
      Expected: 0
    },
    {
      Expression: '   (      [)',
      Actual: checkBraces('   (      [)'),
      Expected: 1
    }
  ]
  console.table(data)
  const testIsOk = data.filter(item => item.Expected === item.Actual)
  console.log(testIsOk.length === data.length ? 'Test is OK' : 'Test failed')
}

test()

deepCopy.js

/**
 * See demo (https://jsfiddle.net/yarkov_aleksei/zvja46y3/)
 */

const isObject = value =>
  typeof value !== 'function' &&
  value instanceof Object &&
  !Array.isArray(value)

function deepCopy(value) {
  if (!isObject(value)) {
    return value
  }
  const clone = {}
  for (const i in value) {
    if (isObject(value[i])) {
      clone[i] = deepCopy(value[i])
    } else if (Array.isArray(value[i])) {
      clone[i] = [...value[i]]
    } else {
      clone[i] = value[i]
    }
  }
  return clone
}

function test() {
  const testObject = {
    item: 'Item name',
    nestedObject: {
      nestedKey: 'Key name'
    },
    nestedArray: [1, 2, 3]
  }
  const cloneObj = deepCopy(testObject)
  const testIsOk =
    cloneObj.nestedObject !== testObject.nestedObject &&
    cloneObj.nestedArray !== testObject.nestedArray
  console.log(testIsOk ? 'Test is OK' : 'Test failed')
}

test()

refactoring.js

/**
 * See demo (https://jsfiddle.net/yarkov_aleksei/2daj3s4y/)
 */

// Before
function func(s, a, b) {
  if (s.match(/^$/)) {
    return -1
  }

  var i = s.length - 1
  var aIndex = -1
  var bIndex = -1

  while (aIndex == -1 && bIndex == -1 && i > 0) {
    if (s.substring(i, i + 1) == a) {
      aIndex = i
    }
    if (s.substring(i, i + 1) == b) {
      bIndex = i
    }
    i = i - 1
  }

  if (aIndex != -1) {
    if (bIndex == -1) {
      return aIndex
    } else {
      return Math.max(aIndex, bIndex)
    }
  }

  if (bIndex != -1) {
    return bIndex
  } else {
    return -1
  }
}

// After
function func(s, a, b) {
  if (!s || (!a || !b)) {
    return -1
  }

  return Math.max(s.lastIndexOf(a), s.lastIndexOf(b))
}

function test() {
  const one = func('string', 'st', 'ng')
  const two = func('', 'st', 'ng')
  const three = func('string', '', 'ng')
  const four = func('string', 'st', '')
  const testIsOk = one === 4 && two === -1 && three === -1 && four === -1
  console.log(testIsOk ? 'Test is OK' : 'Test failed')
}

test()