JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" class="zip-val" />

JavaScript

$(".zip-val").keyup(function(e) {
    if(e.keyCode == 8)
    {
    	if($(this).val().length == 6){
        var newText = $(this).val().substring(0 , 5);
        $(this).val(newText);
      }
    }
    else if($(this).val().length == 6) {
        var newText = $(this).val().substring(0 , 5) + '-' + $(this).val().substring(5);
        $(this).val(newText);
    }
});