new Quill('#quilljs-container', {
    modules: {
        toolbar: [
           ['bold', 'italic', 'underline', 'strike'],        // toggled buttons
           ['blockquote', 'code-block', 'link'],

           [{ 'header': 1 }, { 'header': 2 }],               // custom button values
           [{ 'list': 'ordered'}, { 'list': 'bullet' }],
           [{ 'script': 'sub'}, { 'script': 'super' }],      // superscript/subscript
           [{ 'indent': '-1'}, { 'indent': '+1' }],          // outdent/indent
           [{ 'direction': 'rtl' }],                         // text direction

           [{ 'color': [] }, { 'background': [] }],          // dropdown with defaults from theme
           [{ 'font': [] }],
           [{ 'align': [] }],

           ['clean']                                         // remove formatting button
       ]
    },
    theme: 'snow'
});

<!-- Style -->
<link href="https://cdn.quilljs.com/1.0.0/quill.snow.css" rel="stylesheet">

<!-- quill js container -->
<div id="quilljs-container">  </div>

<!-- Add quill js on the project -->
<script src="https://cdn.quilljs.com/1.0.0/quill.js"></script>

// Add fonts to whitelist
let Font = Quill.import('formats/font');
// We do not add Sans Serif since it is the default
Font.whitelist = ['inconsolata', 'roboto', 'mirza', 'arial'];
Quill.register(Font, true);


// We can now initialize Quill with something like this:
let quillObj = new Quill('#quilljs-container', {
  modules: {
    toolbar: '#toolbar-container'
  },
  placeholder: 'This is a font test...',
  theme: 'snow'
});

<!-- Style -->
<link href="https://fonts.googleapis.com/css?family=Roboto" rel="stylesheet">
<style>
  /* Set dropdown font-families */
  
  #toolbar-container .ql-font span[data-label="Sans Serif"]::before {
    font-family: "Sans Serif";
  }
  
  #toolbar-container .ql-font span[data-label="Inconsolata"]::before {
    font-family: "Inconsolata";
  }
  
  #toolbar-container .ql-font span[data-label="Roboto"]::before {
    font-family: "Roboto";
  }
  
  #toolbar-container .ql-font span[data-label="Mirza"]::before {
    font-family: "Mirza";
  }
  
  #toolbar-container .ql-font span[data-label="Arial"]::before {
    font-family: "Arial";
  }
  /* Set content font-families */
  
  .ql-font-inconsolata {
    font-family: "Inconsolata";
  }
  
  .ql-font-roboto {
    font-family: "Roboto";
  }
  
  .ql-font-mirza {
    font-family: "Mirza";
  }
  
  .ql-font-arial {
    font-family: "Arial";
  }
  /* We do not set Sans Serif since it is the default font */
</style>
<link href="https://cdn.quilljs.com/1.0.0/quill.snow.css" rel="stylesheet">


<div id="standalone-container">
  <div id="toolbar-container">
    <span class="ql-formats">
      <select class="ql-font">
        <option selected>Sans Serif</option>
        <option value="inconsolata">Inconsolata</option>
        <option value="roboto">Roboto</option>
        <option value="mirza">Mirza</option>
        <option value="arial">Arial</option>
      </select>
      <select class="ql-size"></select>
    </span>
    <span class="ql-formats">
      <button class="ql-bold"></button>
      <button class="ql-italic"></button>
      <button class="ql-underline"></button>
      <button class="ql-strike"></button>
    </span>
    <span class="ql-formats">
      <select class="ql-color"></select>
      <select class="ql-background"></select>
    </span>
    <span class="ql-formats">
      <button class="ql-blockquote"></button>
      <button class="ql-code-block"></button>
      <button class="ql-link"></button>
    </span>
    <span class="ql-formats">
      <button class="ql-header" value="1"></button>
      <button class="ql-header" value="2"></button>
    </span>
    <span class="ql-formats">
      <button class="ql-list" value="ordered"></button>
      <button class="ql-list" value="bullet"></button>
      <button class="ql-indent" value="-1"></button>
      <button class="ql-indent" value="+1"></button>
    </span>
    <span class="ql-formats">
      <button class="ql-direction" value="rtl"></button>
      <select class="ql-align"></select>
    </span>
    <span class="ql-formats">
      <button class="ql-script" value="sub"></button>
      <button class="ql-script" value="super"></button>
    </span>
    <span class="ql-formats">
      <button class="ql-clean"></button>
    </span>
  </div>
</div>
<!-- quill js container -->
<div id="quilljs-container"></div>
<!-- Add quill js on the project -->
<script src="https://cdn.quilljs.com/1.0.0/quill.js"></script>