How to trigger an SVG animation with JavaScript? (No jQuery)

Question

I have an SVG line path animated with this sample I found:

svg {
  position: absolute;
  width: 100%;
  height: 100%;
  left: 0%;
  top: 0%;
  display: block;
  background: transparent;
}

.path {
  stroke: black;
  stroke-dasharray: 290;
  stroke-dashoffset: 130;
  animation: dash 6s 0s forwards infinite;
  stroke-width: 2px;
  stroke-linecap: round;
  stroke-linejoin: round;
}

@keyframes dash {
  from {
    stroke-dashoffset: 290;
  }
  to {
    stroke-dashoffset: 0;
  }
}

<svg viewbox="0 0 25 100" xmlns="http://www.w3.org/2000/svg">
<path class="path" d="M0 50 L 12 50, 12 0, 25 0" fill="transparent"></path>
</svg>

It works fine but it's triggered when the page loads. Is there a way (let's say with a button) to trigger this animation using JavaScript?

I can handle JS but I'm a noob with CSS and SVG animations.

Can anybody give me an example of how I can do it with my actual CSS?

Answer 1

You could also use SMIL animation syntax instead of CSS animation. This admittedly has the downside of not running in Microsoft browsers (both IE and Edge).

var animation = document.getElementById("dash");

function showSVG() {
  animation.beginElement();
}

svg {
  position: relative;
  width: 100%;
  height: 150px;
  left: 0%;
  top: 0%;
  display: block;
  background: transparent;
}

.path {
  stroke: black;
  stroke-dasharray: 290;
  stroke-dashoffset: 290;
  stroke-width: 2px;
  stroke-linecap: round;
  stroke-linejoin: round;
}

<button id="button" onclick="showSVG()">Click</button>
<svg id="svg" viewbox="0 0 25 100" xmlns="http://www.w3.org/2000/svg">
  <path class="path" d="M0 50 L 12 50, 12 0, 25 0" fill="transparent">
  <animate id="dash" 
    attributeName="stroke-dashoffset"
    from="290" to="0"
    begin="indefinite" 
    dur="6s" 
    fill="freeze" />
  </path>
</svg>

This animation runs once every time you click. If you want it to repeat in fixed intervals, like CSS animation-repeat: infinite prescribes, use

<animate id="dash" attributeName="stroke-dashoffset"
    from="290" to="0"
    begin="indefinite" dur="6s" repeatCount="indefinite" />

Answer 2

svg {
    position: absolute;
    width: 100%;
    height: 100%;
    left: 0%;
    top: 0%;
    display: block;
    background: transparent;
}

.path {
    stroke: black;
    stroke-dasharray: 290;
    stroke-dashoffset: 130;
    stroke-width: 2px;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-dashoffset: 290;
}

.animated {
    animation: dash 6s 0s forwards infinite;
    stroke-dashoffset: 0;
}

@keyframes dash {
    from {
        stroke-dashoffset: 290;
    }
    to {
        stroke-dashoffset: 0;
    }
}

Then you can add the class .animated to your path with js whenever you need it.