Return true if the passed string is a valid US phone number. The user may fill out the form field any way they choose as long as it is a valid US number. The following are examples of valid formats for US numbers (refer to the tests below for other variants): 555-555-5555 ||| (555)555-5555 ||| (555) 555-5555 ||| 555 555 5555 ||| 5555555555 ||| 1…

Validate US Telephone Numbers

//javascript
function telephoneCheck(str) {
   
  if (!balancedParens(str)){
    return false;
  }
  
  //remove whitespace
  var newStr = str.replace(/\s/g, '');
  
  //validation  regular expression or pattern
  var patt = /^1?\(?\d{3}-?\)?\d{3}-?\d{4}$/;
  
  return patt.test(newStr);

}



telephoneCheck("555-555-5555");

function balancedParens(string){  
  var stack = [];
  var pairs = {
    '[':']',
    '{':'}',
    '(':')'
  };
  var closers = {
    ')': 1,
    ']': 1,
    '}': 1
  };
  for(var i = 0; i < string.length; i++){
    var cur = string[i];
    if(pairs[cur]){
      console.log(cur,"----",pairs[cur]);
      stack.push(pairs[cur]);
    } else if(cur in closers){
      if(stack[stack.length -1] === cur){
        stack.pop();
      } else{
        return false;
      }
    }
  }
  return !stack.length;
}

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