Solve matching parentheses problem.

nesting_verify.js

var results = new Array();
var l = console.log.bind(console)

//Task
results.push(verify("---(++++)----"));// -> true
results.push(verify(""));// -> true
results.push(verify("before ( middle []) after "));// -> false
results.push(verify(") ("));// -> false
results.push(verify("} {"));// -> true
results.push(verify("<(   >)"));// -> false
results.push(verify("(  [  <>  ()  ]  <>  )"));// -> true
results.push(verify("   (      [)"));// -> false

if(JSON.stringify(results) === JSON.stringify([true, true, true, false, true, false, true, false]){
  l('Success!')
}else{
  l('Fail!')
}



//Solution
function verify(str){
    stack = []
    opening = ['<', '[', '('] 
    closing = ['>', ']', ')'] 
    pairs = {'>':'<', ']':'[', ')':'('}
    for(var i = 0, len = str.length; i < len; i++){
        if(opening.indexOf(str[i]) > -1) {
            stack.push(str[i])
        }else if(closing.indexOf(str[i]) > -1){
            if(stack.length === 0) return false;
            translatedCh = pairs[str[i]]
            stackTop = stack[stack.length-1]
            if (stackTop === translatedCh){
                stack.pop()
            }else{
                return false
            }
        }
    }
    return stack.length === 0;
}