대소문자 변경예제

<fieldset>

    <legend>입력창</legend>

      <input type="text" id="memo" size="50" />

</fieldset><br>

<div id="result3"> </div>

<button onclick="memoPrint();">입력</button>

<button onclick="memoUpper();">대문자로 변경</button>

<button onclick="memoLower();">소문자로 변경</button>

<script>

    let str4=document.getElementById("memo");

    let upperLower=document.getElementById("result3");

    function memoPrint() {

        upperLower.innerHTML=str4.value;        

    }

    //let changeStr='';

    function memoUpper(){      

        upperLower.innerHTML=str4.value.toUpperCase();

    }

    function memoLower(){

        upperLower.innerHTML=str4.value.toLowerCase();

    }

</script>