[SOLVED] Add a dollar sign with an Event Listener

Add a dollar sign with an Event Listener

I am very new to this - how can I add a dollar sign using an event listener? Currently I have:

let dol = document.querySelector('#dollar');

dol.addEventListener('keyup', function(e) { {
  dol.value = "$" + dol.value;
  }
});

But this is adding a dollar sign for every digit.
I only need the one in front.

Solution

eten : Just check with dol.value.startsWith("$")...

let dol = document.querySelector('#dollar')
  ;
dol.addEventListener('keyup', e =>
  {
  if (!dol.value.startsWith('$'))
    dol.value = "$" + dol.value; 
  });

label {
  margin      : .6rem;
  display     : block;
  font-size   : .8rem;
  font-weight : bold;
  }
label * {
  box-sizing : border-box;
  display    : block;
  font-size  : 1rem;
  width      : 16rem;
  padding    : .2rem .3rem;
  }

<label>
  input for dollars...
  <input id="dollar" type="text" >
</label>

const myForm = document.querySelector('#my-Form')
  ;
myForm.addEventListener('input', e =>  // for any input on form...
  {
  if ( ['money_1','money_2'].includes(e.target.name)
    && !e.target.value.startsWith('$')
    ){
    e.target.value = "$" + e.target.value.trim();
    
    if (e.target.value === '$') // you may need this one...
      e.target.value = '';  
    }

  });
myForm.addEventListener('submit', e =>
  {
  e.preventDefault(); // disable form submision.
  
  // get values...
  console.clear();
  console.log('money_1 = ', myForm.money_1.value );
  console.log('money_2 = ', myForm.money_2.value );
  });

label {
  margin      : .6rem;
  display     : block;
  font-size   : .8rem;
  font-weight : bold;
  }
label * {
  box-sizing : border-box;
  display    : block;
  font-size  : 1rem;
  width      : 16rem;
  padding    : .2rem .3rem;
  }

<form id="my-Form">
  <label>
    input 1 for dollars...
    <input name="money_1" type="text" required >
  </label>
  <label>
    input 2 for dollars...
    <input name="money_2" type="text" required>
  </label>
  
  <button>submit</button>
</form>