document.getElementById('input').addEventListener('keydown',function(event){
  event.preventDefault();
  var stateTree = {
   0 : ['-','+','[0-9]'],
   ... //  basicly declare here possible regexp's per length
  };

  var text = this.value +''+ event.key;
  var array = stateTree[text.length];
  array.map( function(item){
    const match = new RegExp(item, 'g');
    if( text.match(match) ){ this.value = text }
  });

})