open brackets must be closed in the correct order in javascript

December 6, 2021

s = ['[',']','{','}','(',')']
copied=s;
console.log(copied.length);
var output;
for(i=0;i<s.length;i++){
    console.log("calling function",i);
   
    different();

}

function different(){
   
    if(copied[0]=='(' && copied[1]==')'){
        copied.splice(0,2);
        output= "valid";
        console.log("checking",copied);
}
else if(copied[0]=='{' && copied[1]=='}'){
    copied.splice(0, 2);
    output= "valid";
}
else if(copied[0]=='[' && copied[1]==']'){
    copied.splice(0, 2);
    output= "valid";
    console.log("checking",copied);

}
else {
    output= "invalid";
}
}

console.log(copied);
console.log(copied.length);
console.log("result is ",output);

i am getting the following output

calling function 0

checking [ ‘{‘, ‘}’, ‘(‘, ‘)’ ]

calling function 1

[ ‘(‘, ‘)’ ]

result is valid

The problem is for loop runs only twice but it is supposed to run 6 times.

>Solution :

Fixed a few issues with the code. The primary one being that the OP’s different() function examines the same part of the array, no matter the state of the loop…

const s = ['[', ']', '{', '}', '(', ')', '[', '***']

for (i = 0; i < s.length - 1; i += 2) {
  let result = different(s[i], s[i + 1]);
  console.log(result)
}

function different(a, b) {
  let match =
    (a === '(' && b === ')') ||
    (a === '[' && b === ']') ||
    (a === '{' && b === '}')
  return `"${a}" and "${b}" ${match ? '' : 'do not'} match`
}

A more scalable approach would put represent the syntax in data, like this…

const s = ['[', ']', '{', '}', '(', ')', '[', '***']
const delimiters = {
  '[': ']',
  '(': ')',
  '{': '}',
}

for (i = 0; i < s.length - 1; i += 2) {
  let result = different(s[i], s[i + 1]);
  console.log(result)
}

function different(a, b) {
  let match = delimiters[a] === b;
  return `"${a}" and "${b}" ${match ? '' : 'do not'} match`
}