JSFiddle - React, Tailwind, and code Playground

by Ilia Lesnykh

HTML

<form name="forma1">
Длина <input type="text" name="t1" size="10"><br/><br/>
Ширина <input type="text" name="t2" size="10"><br/><br/>
<input type="button" name="button" value="Вычислить" onClick="areaRect();"><br/><br/>
Площадь <input type="text" name="res" size="10"><br/><br/>
<input type="button" name="button" value="Сброс" onClick="reset();">
</form>

JavaScript

function areaRect(){
	var a=document.forma1.t1.value;
	var b=document.forma1.t2.value;
	var s=a*b;
	document.forma1.res.value=s;
}
function reset(){
	document.forma1.res.value=" ";
}