问用HTML和JavaScript实现勾股定理计算器

EN

function do_things() {
  var a = parseFloat(document.getElementById("a").value);
  var b = parseFloat(document.getElementById("b").value);
  var c = parseFloat(document.getElementById("c").value);
  var output = document.getElementById("output");

  if (a=0, b>0){
    var c = Math.sqrt(c*c - b*b)
    var node = document.createElement("LI");                 // Create a <li> node
    var textnode = document.createTextNode(c);              // Create a text node
    node.appendChild(textnode);                              // Append the text to <li>
    document.getElementById("output").appendChild(node);
  } else if (c=0, b>0){
    var c = Math.sqrt(a*a + b*b)
    console.log(0)
    var node = document.createElement("LI");                 // Create a <li> node
    var textnode = document.createTextNode(c);              // Create a text node
    node.appendChild(textnode);                              // Append the text to <li>
    document.getElementById("output").appendChild(node);
  }
}

<h1>Calc</h1>
<p1>Calculate the Hypotnuse given the A and B value</p1>
<p>Side A: <input type="text" id="a"/></p>
<br>
<p>Side B: <input type="text" id="b"/></p>
<br>
<p>Hypotnuse: <input type="text" id="c"/></p>
<br>
 <button type="button" onclick="do_things()">Find the missing value</button>
<br>
<p id="output">The Missing hypotnuse</p>