計算機

by wales

HTML

<form name="form1" onsubmit="return false;">
  <input name="a" type="number" step="any" />
  <select name="sel"> 
<option value="+">+</option> 
<option value="-">-</option> 
<option value="*">*</option> 
<option value="/">/</option> 
<option value="%">%</option> 
</select>
  <input name="b" type="number" step="any" />
  <button onclick="doCheck()">=</button>
</form>
<div id="info"></div>

JavaScript

function doCheck() {
  var operate = document.getElementsByName('sel')[0];
  var val_a = document.getElementsByName('a')[0];
  var val_b = document.getElementsByName('b')[0];
  info.innerHTML = eval(val_a.value + operate.value + val_b.value);
}