<!-- https://github.com/eugenkiss/7guis/wiki#temperature-converter --> <input value={c} on:input="{e => setBothFromC(e.target.value)}" type=number> °c = <input value={f} on:input="{e => setBothFromF(e.target.value)}" type=number> °f <style> input { width: 5em; } </style> <script> let c = 0; let f = 32; function setBothFromC(value) { c = +value; f = +(32 + (9 / 5 * c)).toFixed(1); } function setBothFromF(value) { f = +value; c =+(5 / 9 * (f - 32)).toFixed(1); } </script>