ValidParentheses.js

// Problem link: https://leetcode.com/problems/valid-parentheses/

const isValid = (string) => {
    // create a hashMap to store the valid match   
    const bracketsMap = {
            '(': ')',
            '{': '}',
            '[': ']'
          }
    // create a stack data structure with array
    let stack = []
    
    // loop through the string 
    for(let char of string){
        //if character is in the hashMap, push the character in the stack
        if(bracketsMap[char]){
            stack.push(char)
            
        // when stack is not empty and 
        //the topmost item of the stack key in the hashMap is equal to the character
        }else if(stack.length > 0 && bracketsMap[stack[stack.length-1]] === char){
        
        // removed the last element     
          stack.pop()
        }else{
         
        //if the character not found in the hashmap return false
            return false
        }
    }
    
   //when stack is empty, it means all matching brackets are found 
  return stack.length === 0

}