A Pen by Matthew Van Dusen.

index.html

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            <pre class="numbers linenums prettyprint prettyprinted"><ol class="linenums"><li class="L0"><code class="css"><span class="pln">describe</span><span class="pun">(</span><span class="str">'Connection'</span><span class="pun">,</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">(){</span></code></li><li class="L1"><code class="css"><span class="pln">  </span><span class="kwd">var</span><span class="pln"> db </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Connection</span></code></li><li class="L2"><code class="css"><span class="pln">    </span><span class="pun">,</span><span class="pln"> tobi </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">User</span><span class="pun">(</span><span class="str">'tobi'</span><span class="pun">)</span></code></li><li class="L3"><code class="css"><span class="pln">    </span><span class="pun">,</span><span class="pln"> loki </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">User</span><span class="pun">(</span><span class="str">'loki'</span><span class="pun">)</span></code></li><li class="L4"><code class="css"><span class="pln">    </span><span class="pun">,</span><span class="pln"> jane </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">User</span><span class="pun">(</span><span class="str">'jane'</span><span class="pun">);</span></code></li><li class="L5"><code class="css"></code></li><li class="L6"><code class="css"><span class="pln">  beforeEach</span><span class="pun">(</span><span class="kwd">function</span><span class="pun">(</span><span class="kwd">done</span><span class="pun">){</span></code></li><li class="L7"><code class="css"><span class="pln">    db</span><span class="pun">.</span><span class="pln">clear</span><span class="pun">(</span><span class="kwd">function</span><span class="pun">(</span><span class="pln">err</span><span class="pun">){</span></code></li><li class="L8"><code class="css"><span class="pln">      </span><span class="kwd">if</span><span class="pln"> </span><span class="pun">(</span><span class="pln">err</span><span class="pun">)</span><span class="pln"> </span><span class="kwd">return</span><span class="pln"> </span><span class="kwd">done</span><span class="pun">(</span><span class="pln">err</span><span class="pun">);</span></code></li><li class="L9"><code class="css"><span class="pln">      db</span><span class="pun">.</span><span class="pln">save</span><span class="pun">([</span><span class="pln">tobi</span><span class="pun">,</span><span class="pln"> loki</span><span class="pun">,</span><span class="pln"> jane</span><span class="pun">],</span><span class="pln"> </span><span class="kwd">done</span><span class="pun">);</span></code></li><li class="L0"><code class="css"><span class="pln">    </span><span class="pun">});</span></code></li><li class="L1"><code class="css"><span class="pln">  </span><span class="pun">})</span></code></li></ol></pre>
          </div>

style.sass

/* custom light solarize theme for public use  in .sass format
 *
 * Name:  Matthew
 * Email:   imagineux@gmail.com
 * 
 */
$black: hsla(0, 0%, 15%, 1)
$dark-gray: hsla(208, 12%, 25%, 1)
$medium-gray: hsla(225, 3%, 26%, 1)
$gray: hsla(0, 0%, 60%, 1)
$light-gray: hsla(195, 29%, 97%, 1)
$pre-gray: hsla(195, 29%, 94%, 1)
$white: hsla(0, 100%, 100%, 1)
$light-red: hsla(0, 80%, 64%, 1)
$red: hsla(0, 80%, 56%, 1)
$light-green: hsla(138, 54%, 59%, 1)
$green: hsla(138, 54%, 49%, 1)
$light-blue: hsla(205, 50%, 47%, 1)
$blue: hsla(205, 51%, 40%, 1)
$dark-blue: hsla(205, 51%, 30%, 1)
$gray-button: hsla(208, 12%, 76%, 1)
$gray-border: hsla(210, 12%, 71%, 1)
$light-yellow: hsla(52, 100%, 87%, 1)

// font stuff
$base-font-color: $gray
$base-accent-color: $gray
body
  background: $dark-gray

.pln 
  color: #bd3613 

.str 
  color: #269186 

.kwd 
  color: #859900 

.com 
  color: #586175
  font-style: italic 

.typ 
  color: #b58900 

.lit 
  color: #2aa198 

.pun 
  color: #839496 

.opn 
  color: #839496 

.clo 
  color: #839496 

.tag 
  color: #268bd2 

.atn 
  color: #586175 

.atv 
  color: #2aa198 

.dec 
  color: #268bd2 

.var 
  color: #268bd2 

.fun 
  color: #FF0000 

/* Put a border around 
  printed code snippets. */
pre.prettyprint 
  padding: 0.5rem 0.5rem

/* Specify class=linenums on a pre to get line numbering */
ol.linenums 
  color: #4c666c
  overflow: hidden

ol.linenums li
  line-height: 18px
  margin: 0 0 0.3125rem 0.75rem
  overflow: hidden
  flex: 1
///////////////////////////////////////////////

.linenums > li
  opacity: 0.7
  white-space: nowrap
  overflow: hidden
  border-right: 1px solid
  animation: typing 3s steps(26, end), blink-caret 1s step-end 3s
  &:nth-child(2)
    animation: typingMid 3s steps(23, end), blink-caret 1s step-end 3s
    animation-delay: 3s
    animation-fill-mode: backwards
  &:nth-child(3)
    animation: typingMid 3s steps(26, end), blink-caret 1s step-end 2s
    animation-delay: 6s
    animation-fill-mode: backwards
  &:nth-child(4)
    animation: typingMid 3s steps(26, end), blink-caret 1s step-end 2s
    animation-delay: 9s
    animation-fill-mode: backwards
  &:nth-child(5)
    animation: typingMid 3s steps(26, end), blink-caret 1s step-end 2s
    animation-delay: 12s
    animation-fill-mode: backwards
  &:nth-child(6)
    animation: typingNone 0.1s steps(1, end), blink-caret 1s step-end 2s
    animation-delay: 15s
    animation-fill-mode: backwards
  &:nth-child(7)
    animation: typingMid 3s steps(22, end), blink-caret 1s step-end 2s
    animation-delay: 15.1s
    animation-fill-mode: backwards
  &:nth-child(8)
    animation: typingMid 3s steps(22, end), blink-caret 1s step-end 2s
    animation-delay: 18.1s
    animation-fill-mode: backwards
  &:nth-child(9)
    animation: typingMid 3s steps(22, end), blink-caret 1s step-end 2s
    animation-delay: 21.1s
    animation-fill-mode: backwards
  &:nth-child(10)
    animation: typingMid 3s steps(22, end), blink-caret 1s step-end 2s
    animation-delay: 24.1s
    animation-fill-mode: backwards
  &:nth-child(11)
    animation: typingNone 1s steps(3, end), blink-caret 1s step-end 2s
    animation-delay: 27.1s
    animation-fill-mode: backwards
  &:nth-child(12)
    animation: typingLast 1s steps(3, end), blink-caret 1s step-end infinite
    animation-delay: 30.1s
    animation-fill-mode: both

@keyframes typingMid
  from
    width: 0%
  to
    width: 100%


@keyframes typing
  from
    width: 0
  to
    width: 320px


@keyframes typingLast
  from
    width: 0
  to
    width: 10px


@keyframes typingNone
  from
    width: 0
  to
    width: 10px


@keyframes blink-caret
  from, to
    border-color: transparent
  50%
    border-color: black
//////////////////////////////////////////////////////
  
.code-editor
  display: flex
  flex-direction: row
  width: 34rem
  height: 20rem
  margin: 4rem auto
  position: relative
  border-radius: 5px 5px 0 0
  background: $white
  &::before
    content: ''
    z-index: 20
    background: $pre-gray
    padding-top: 6px
    position: absolute
    top: -1.875rem
    left: 0
    right: 0
    height: 1.875rem
    border-radius: 5px 5px 0 0
    content: ''
    z-index: 2
  &::after
    content: ''
    background: #f5f8fa
    padding-top: 6px
    position: absolute
    top: 0
    left: 0
    bottom: 0
    width: 1.875rem
    z-index: 1
span.control::before 
  content: ''
  position: absolute
  top: -1rem
  left: 0
  z-index: 30
  padding: 6px
  border-radius: 20px
span.control
  &:nth-child(1):before 
    margin-left: 15px
    background-color: $red
  &:nth-child(2):before 
    margin-left: 35px
    background-color: $light-yellow
  &:nth-child(3):before 
    margin-left: 55px
    background-color: $green

pre.numbers
  display: flex
  flex-direction: column
  margin: 0 
  opacity: .65

code.css
  display: flex-direction
  flex: 1

Typing-animation--Pretty.markdown

Typing animation- Pretty

reduse case using generated utput from google prettyify

A Pen by Matthew Van Dusen on CodePen.

License.