Código JS:
var titulo = document.querySelector(".titulo");
titulo.textContent = "Aparecida Nutricionista";
var paciente = document.querySelector("#primeiro-paciente");
var tdPeso = paciente.querySelector(".info-peso");
var peso = tdPeso.textContent;
var tdAltura = paciente.querySelector(".info-altura");
var altura = tdAltura.textContent;
var tdImc = paciente.querySelector(".info-imc");
var imc = peso / (altura*altura);
tdImc.textContent = imc;
Código html:
<!DOCTYPE html>
<html lang="pt-br">
<head>
<meta charset="UTF-8">
<title>Aparecida Nutrição</title>
<link rel="icon" href="favicon.ico" type="image/x-icon">
<link rel="stylesheet" type="text/css" href="css/reset.css">
<link rel="stylesheet" type="text/css" href="css/index.css">
</head>
<body>
<header>
<div class="container">
<h2 class="titulo">Aparecida Nutrição</h2>
</div>
</header>
<main>
<section class="container">
<h2>Meus pacientes</h2>
<table>
<thead>
<tr>
<th>Nome</th>
<th>Peso(kg)</th>
<th>Altura(m)</th>
<th>Gordura Corporal(%)</th>
<th>IMC</th>
</tr>
</thead>
<tbody id="tabela-pacientes">
<tr class="paciente" >
<td class="info-nome">Paulo</td>
<td class="info-peso">100</td>
<td class="info-altura">2.00</td>
<td class="info-gordura">10</td>
<td class="info-imc">0</td>
</tr>
<tr class="paciente" >
<td class="info-nome">João</td>
<td class="info-peso">80</td>
<td class="info-altura">1.72</td>
<td class="info-gordura">40</td>
<td class="info-imc">0</td>
</tr>
<tr class="paciente" >
<td class="info-nome">Erica</td>
<td class="info-peso">54</td>
<td class="info-altura">1.64</td>
<td class="info-gordura">14</td>
<td class="info-imc">0</td>
</tr>
<tr class="paciente">
<td class="info-nome">Douglas</td>
<td class="info-peso">85</td>
<td class="info-altura">1.73</td>
<td class="info-gordura">24</td>
<td class="info-imc">0</td>
</tr>
<tr class="paciente" >
<td class="info-nome">Tatiana</td>
<td class="info-peso">46</td>
<td class="info-altura">1.55</td>
<td class="info-gordura">19</td>
<td class="info-imc">0</td>
</tr>
</tbody>
</table>
</section>
</main>
<script src="js/principal.js" ></script>
</body>
</html>