input.html

<input type="text" id="myinput" />

numberInput.js

var input = document.getElementById('myinput'),
    availIndices = [1,2,3,6,7,8,10,11,12,13],
    placeholderAry = "(___) ___-____".split(""),
    counter = 0,
    keyPressed,
    inputAry,
    indexToReplace;
    
input.addEventListener('focus', function(){
input.placeholder = placeholderAry.join("");
    input.addEventListener('keydown', function(e){
    e.preventDefault();
    keyPressed = e.keyCode 
    if(e.keyCode === 8){
        if(counter > 0){
        counter--;
        inputAry = input.value.split("");
        indexToReplace = availIndices[counter];
        inputAry.splice(indexToReplace, 1, "_");
        placeHolderAry = inputAry;
        input.value = inputAry.join("")
        input.setSelectionRange(indexToReplace,indexToReplace);
        }
    }
    
    if(keyPressed > 47 && keyPressed < 58){
      if(counter === 0){
        placeholderAry = "(___) ___-____".split("");
      }
      if(counter < 10){
        indexToReplace = availIndices[counter];
        placeholderAry[indexToReplace] = String.fromCharCode(keyPressed);
        input.value = placeholderAry.join("");
        input.setSelectionRange(indexToReplace+1,indexToReplace+1);
        counter++;
     }     
  }
});