1var assert = require('assert');
2
3function validateSymbols(str) {
4  let map = {
5    ')': '(',
6    ']': '[',
7    '}': '{',
8  };
9  let stack = [];
10  for (let i = 0; i < str.length; i++) {
11    if (str[i] === '(' || str[i] === '[' || str[i] === '{') {
12      stack.push(str[i]);
13    } else {
14      if (stack[stack.length - 1] === map[str[i]]) {
15        stack.pop();
16      } else return false;
17    }
18  }
19  return stack.length === 0 ? true : false;
20}
21
22try {
23  assertIsFunction(validateSymbols);
24
25  console.log('PASSED: ' + '`validateSymbols` is a function');
26} catch (err) {
27  console.log(err);
28}
29
30try {
31  assert.equal(validateSymbols('[]'), true);
32
33  console.log('PASSED: ' + "`validateSymbols('[]')` should return `true`");
34} catch (err) {
35  console.log(err);
36}
37
38try {
39  assert.equal(validateSymbols('{{[]}}'), true);
40
41  console.log('PASSED: ' + "`validateSymbols('{{[]}}')` should return `true`");
42} catch (err) {
43  console.log(err);
44}
45
46try {
47  assert.equal(validateSymbols('[[}}'), false);
48
49  console.log('PASSED: ' + "`validateSymbols('[[}}')` should return `false`");
50} catch (err) {
51  console.log(err);
52}
53
54function assertIsFunction(f) {
55  return typeof f === 'function';
56}