title: Issue regarding innerHTML showing as Typeerror on the console
body: <p>I just started to code, and I followed a tutorial video for a coding in javascript. However, the console shows that I have &quot;Uncaught TypeError: Cannot set property 'innerHTML' of null at app.js:97.&quot; I don't understand why. I checked for typos, but there seemed to be none. I hope you guys know why this error keeps coming up. Thanks.</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>//items
  const menu = [
    {
      id: 1,
      title: "buttermilk pancakes",
      category: "breakfast",
      price: 15.99,
      img: "./images/item-1.jpeg",
      desc: `I'm baby woke mlkshk wolf bitters live-edge blue bottle, hammock freegan copper mug whatever cold-pressed `,
    },
    {
      id: 2,
      title: "diner double",
      category: "lunch",
      price: 13.99,
      img: "./images/item-2.jpeg",
      desc: `vaporware iPhone mumblecore selvage raw denim slow-carb leggings gochujang helvetica man braid jianbing. Marfa thundercats `,
    },
    {
      id: 3,
      title: "godzilla milkshake",
      category: "shakes",
      price: 6.99,
      img: "./images/item-3.jpeg",
      desc: `ombucha chillwave fanny pack 3 wolf moon street art photo booth before they sold out organic viral.`,
    },
    {
      id: 4,
      title: "country delight",
      category: "breakfast",
      price: 20.99,
      img: "./images/item-4.jpeg",
      desc: `Shabby chic keffiyeh neutra snackwave pork belly shoreditch. Prism austin mlkshk truffaut, `,
    },
    {
      id: 5,
      title: "egg attack",
      category: "lunch",
      price: 22.99,
      img: "./images/item-5.jpeg",
      desc: `franzen vegan pabst bicycle rights kickstarter pinterest meditation farm-to-table 90's pop-up `,
    },
    {
      id: 6,
      title: "oreo dream",
      category: "shakes",
      price: 18.99,
      img: "./images/item-6.jpeg",
      desc: `Portland chicharrones ethical edison bulb, palo santo craft beer chia heirloom iPhone everyday`,
    },
    {
      id: 7,
      title: "bacon overflow",
      category: "breakfast",
      price: 8.99,
      img: "./images/item-7.jpeg",
      desc: `carry jianbing normcore freegan. Viral single-origin coffee live-edge, pork belly cloud bread iceland put a bird `,
    },
    {
      id: 8,
      title: "american classic",
      category: "lunch",
      price: 12.99,
      img: "./images/item-8.jpeg",
      desc: `on it tumblr kickstarter thundercats migas everyday carry squid palo santo leggings. Food truck truffaut  `,
    },
    {
      id: 9,
      title: "quarantine buddy",
      category: "shakes",
      price: 16.99,
      img: "./images/item-9.jpeg",
      desc: `skateboard fam synth authentic semiotics. Live-edge lyft af, edison bulb yuccie crucifix microdosing.`,
    },
  ];
  
  const sectionCenter = document.querySelector("section-center");
  
  window.addEventListener("DOMContentLoaded", function () {
    let displayMenu = menu.map(function (item) {
      // console.log(item);
  
      return `&lt;article class="menu-item"&gt;
            &lt;img src="${item.img}" class="photo" alt=${item.title} /&gt;
            &lt;div class="item-info"&gt;
              &lt;header&gt;
                &lt;h4&gt;${item.title}&lt;/h4&gt;
                &lt;h4 class="price"&gt;${item.price}&lt;/h4&gt;
              &lt;/header&gt;
              &lt;p class="item-text"&gt;
                ${item.desc}
              &lt;/p&gt;
            &lt;/div&gt;
          &lt;/article&gt;`;
    });
    displayMenu = displayMenu.join("");
    sectionCenter.innerHTML = displayMenu;
  });</code></pre>
  <pre class="snippet-code-css lang-css prettyprint-override"><code>/*
  =============== 
  Fonts
  ===============
  */
  @import url("https://fonts.googleapis.com/css?family=Open+Sans|Roboto:400,700&amp;display=swap");
  
  /*
  =============== 
  Variables
  ===============
  */
  
  :root {
    /* dark shades of primary color*/
    --clr-primary-1: hsl(205, 86%, 17%);
    --clr-primary-2: hsl(205, 77%, 27%);
    --clr-primary-3: hsl(205, 72%, 37%);
    --clr-primary-4: hsl(205, 63%, 48%);
    /* primary/main color */
    --clr-primary-5: #49a6e9;
    /* lighter shades of primary color */
    --clr-primary-6: hsl(205, 89%, 70%);
    --clr-primary-7: hsl(205, 90%, 76%);
    --clr-primary-8: hsl(205, 86%, 81%);
    --clr-primary-9: hsl(205, 90%, 88%);
    --clr-primary-10: hsl(205, 100%, 96%);
    /* darkest grey - used for headings */
    --clr-grey-1: hsl(209, 61%, 16%);
    --clr-grey-2: hsl(211, 39%, 23%);
    --clr-grey-3: hsl(209, 34%, 30%);
    --clr-grey-4: hsl(209, 28%, 39%);
    /* grey used for paragraphs */
    --clr-grey-5: hsl(210, 22%, 49%);
    --clr-grey-6: hsl(209, 23%, 60%);
    --clr-grey-7: hsl(211, 27%, 70%);
    --clr-grey-8: hsl(210, 31%, 80%);
    --clr-grey-9: hsl(212, 33%, 89%);
    --clr-grey-10: hsl(210, 36%, 96%);
    --clr-white: #fff;
    --clr-red-dark: hsl(360, 67%, 44%);
    --clr-red-light: hsl(360, 71%, 66%);
    --clr-green-dark: hsl(125, 67%, 44%);
    --clr-green-light: hsl(125, 71%, 66%);
    --clr-gold: #c59d5f;
    --clr-black: #222;
    --ff-primary: "Roboto", sans-serif;
    --ff-secondary: "Open Sans", sans-serif;
    --transition: all 0.3s linear;
    --spacing: 0.25rem;
    --radius: 0.5rem;
    --light-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    --dark-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    --max-width: 1170px;
    --fixed-width: 620px;
  }
  /*
  =============== 
  Global Styles
  ===============
  */
  
  *,
  ::after,
  ::before {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  body {
    font-family: var(--ff-secondary);
    background: var(--clr-grey-10);
    color: var(--clr-grey-1);
    line-height: 1.5;
    font-size: 0.875rem;
  }
  ul {
    list-style-type: none;
  }
  a {
    text-decoration: none;
  }
  img:not(.logo) {
    width: 100%;
  }
  img {
    display: block;
  }
  
  h1,
  h2,
  h3,
  h4 {
    letter-spacing: var(--spacing);
    text-transform: capitalize;
    line-height: 1.25;
    margin-bottom: 0.75rem;
    font-family: var(--ff-primary);
  }
  h1 {
    font-size: 3rem;
  }
  h2 {
    font-size: 2rem;
  }
  h3 {
    font-size: 1.25rem;
  }
  h4 {
    font-size: 0.875rem;
  }
  p {
    margin-bottom: 1.25rem;
    color: var(--clr-grey-5);
  }
  @media screen and (min-width: 800px) {
    h1 {
      font-size: 4rem;
    }
    h2 {
      font-size: 2.5rem;
    }
    h3 {
      font-size: 1.75rem;
    }
    h4 {
      font-size: 1rem;
    }
    body {
      font-size: 1rem;
    }
    h1,
    h2,
    h3,
    h4 {
      line-height: 1;
    }
  }
  /*  global classes */
  
  .btn {
    text-transform: uppercase;
    background: transparent;
    color: var(--clr-black);
    padding: 0.375rem 0.75rem;
    letter-spacing: var(--spacing);
    display: inline-block;
    transition: var(--transition);
    font-size: 0.875rem;
    border: 2px solid var(--clr-black);
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
    border-radius: var(--radius);
  }
  .btn:hover {
    color: var(--clr-white);
    background: var(--clr-black);
  }
  /* section */
  .section {
    padding: 5rem 0;
  }
  
  main {
    min-height: 100vh;
    display: grid;
    place-items: center;
  }
  /*
  =============== 
  Menu
  ===============
  */
  
  .menu {
    padding: 5rem 0;
  }
  .title {
    text-align: center;
    margin-bottom: 2rem;
  }
  .underline {
    width: 5rem;
    height: 0.25rem;
    background: var(--clr-gold);
    margin-left: auto;
    margin-right: auto;
  }
  .btn-container {
    margin-bottom: 4rem;
    display: flex;
    justify-content: center;
  }
  .filter-btn {
    background: transparent;
    border-color: var(--clr-gold);
    font-size: 1rem;
    text-transform: capitalize;
    margin: 0 0.5rem;
    letter-spacing: 1px;
    border-radius: var(--radius);
    padding: 0.375rem 0.75rem;
    color: var(--clr-gold);
    cursor: pointer;
    transition: var(--transition);
  }
  .filter-btn:hover {
    background: var(--clr-gold);
    color: var(--clr-white);
  }
  .section-center {
    width: 90vw;
    margin: 0 auto;
    max-width: 1170px;
    display: grid;
    gap: 3rem 2rem;
    justify-items: center;
  }
  .menu-item {
    display: grid;
    gap: 1rem 2rem;
    max-width: 25rem;
  }
  .photo {
    object-fit: cover;
    height: 200px;
    border: 0.25rem solid var(--clr-gold);
    border-radius: var(--radius);
  }
  .item-info header {
    display: flex;
    justify-content: space-between;
    border-bottom: 0.5px dotted var(--clr-grey-5);
  }
  .item-info h4 {
    margin-bottom: 0.5rem;
  }
  .price {
    color: var(--clr-gold);
  }
  .item-text {
    margin-bottom: 0;
    padding-top: 1rem;
  }
  
  @media screen and (min-width: 768px) {
    .menu-item {
      grid-template-columns: 225px 1fr;
      gap: 0 1.25rem;
      max-width: 40rem;
    }
    .photo {
      height: 175px;
    }
  }
  @media screen and (min-width: 1200px) {
    .section-center {
      width: 95vw;
      grid-template-columns: 1fr 1fr;
    }
    .photo {
      height: 150px;
    }
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
    &lt;head&gt;
      &lt;meta charset="UTF-8" /&gt;
      &lt;meta name="viewport" content="width=device-width, initial-scale=1.0" /&gt;
      &lt;title&gt;Starter&lt;/title&gt;
      &lt;!-- font-awesome --&gt;
      &lt;link
        rel="stylesheet"
        href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.14.0/css/all.min.css"
      /&gt;
      &lt;!-- styles --&gt;
      &lt;link rel="stylesheet" href="styles.css" /&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;section class="menu"&gt;
        &lt;!-- title --&gt;
        &lt;div class="title"&gt;
          &lt;h2&gt;our menu&lt;/h2&gt;
          &lt;div class="underline"&gt;&lt;/div&gt;
        &lt;/div&gt;
        &lt;!-- filter buttons --&gt;
        &lt;!-- menu items --&gt;
        &lt;div class="section-center"&gt;
          &lt;!-- single item --&gt;
          &lt;article class="menu-item"&gt;
            &lt;img src="./menu-item.jpeg" class="photo" alt="menu item" /&gt;
            &lt;div class="item-info"&gt;
              &lt;header&gt;
                &lt;h4&gt;butter milk pancakes&lt;/h4&gt;
                &lt;h4 class="price"&gt;$15&lt;/h4&gt;
              &lt;/header&gt;
              &lt;p class="item-text"&gt;
                Lorem ipsum dolor sit amet consectetur adipisicing elit. Quae
                quasi provident id eligendi vitae unde odit aperiam quam, expedita
                mollitia.
              &lt;/p&gt;
            &lt;/div&gt;
          &lt;/article&gt;
          &lt;!-- end of single item --&gt;
        &lt;/div&gt;
      &lt;/section&gt;
      &lt;!-- javascript --&gt;
      &lt;script src="app.js"&gt;&lt;/script&gt;
    &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>