Develop Reference

Onclick JavaScript Variables

Java script -
I am trying to do this task to get into coding but it's getting a bit confusing
My HTML:
<svg height="400" width="400">
<circle cx="205" cy="203" r="150" fill="black" />
<circle cx="200" cy="200" r="150" fill="#FFCE54"/>
<circle cx="150" cy="160" r="43" fill="black" />
<circle cx="150" cy="160" r="40" fill="white" />
<circle cx="250" cy="160" r="43" fill="black" />
<circle cx="250" cy="160" r="40" fill="white" />
<circle cx="150" cy="160" r="20" fill="black"/>
<circle cx="250" cy="160" r="20" fill="black"/>
<circle cx="145" cy="154" r="5" fill="white"/>
<circle cx="245" cy="154" r="5" fill="white"/>
<path d="M 135.5,260 q 65,45 130,0"
stroke="red" stroke-width="12" fill-opacity="0" />
id="mouth"/>
</svg>
My Javascript code:
faceShape.onclick = function(){
faceShape.setAttribute("fill", "#A0D468");
};
The problem is that when I run the code, I get this error -> Uncaught TypeError: Cannot set property 'onclick' of null"
Please help. Am I doing something wrong?

faceShape does not appear anywhere in your markup. I am guessing based on what you provided that you want to add an id="faceShape" to your <circle> elements or something similar. The error message is saying that there is nothing assigned to faceShape that is why it can't read any property of null.
<svg height="400" width="400">
<circle cx="205" cy="203" r="150" fill="black" />
<circle id="faceShape" cx="200" cy="200" r="150" fill="#FFCE54"/> //added id
<circle cx="150" cy="160" r="43" fill="black" />
<circle cx="150" cy="160" r="40" fill="white" />
<circle cx="250" cy="160" r="43" fill="black" />
<circle cx="250" cy="160" r="40" fill="white" />
<circle cx="150" cy="160" r="20" fill="black"/>
<circle cx="250" cy="160" r="20" fill="black"/>
<circle cx="145" cy="154" r="5" fill="white"/>
<circle cx="245" cy="154" r="5" fill="white"/>
<path d="M 135.5,260 q 65,45 130,0"
stroke="red" stroke-width="12" fill-opacity="0" />
id="mouth"/>
</svg>
I fully changed your javascript to make the click work:
document.getElementById("faceShape").addEventListener("click", change);
function change() {
document.getElementById("faceShape").setAttribute("fill", "#A0D468")
};
Here is a working jsfiddle of what I think you're trying to accomplish: https://jsfiddle.net/g0k5joxq/1/
If not then you can use the code to extrapolate to your circumstances.

Two or more SVGs in a page. How can I animate them on button click?

Same SVG is repeated in carousel multiple times. Carousel is constructed in PHP using a while loop. How can I trigger animation at the click of a next/prev button in carousel?
My jQuery code is as below. It animates only the first <animate> tag. I think I must have explained my whole point.
jQuery(document).ready(function($){
$('.first').click(function(){
$('animate')[0].beginElement();
$('animateTransform')[0].beginElement();
});
});
My SVG code:
<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: Adobe Illustrator 21.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0) -->
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 425 386" style="enable-background:new 0 0 425 386;" xml:space="preserve">
<polygon class="st0" points="356.4,330 399.3,370.8 399.3,82.5 357.3,106.5 "/>
<polygon class="st1" points="63.8,105 63.8,329.3 357.3,329.3 357.3,106.5 "/>
<polygon class="st2" points="21.8,369 62.5,329.3 357.3,329.3 399.3,370.8 20.9,370.8 "/>
<polygon class="st0" points="63.8,329.2 20.9,370.8 20.9,82.5 63.8,105 "/>
<g>
<line class="st3" id="line1" x1="65.2" y1="76.3" x2="180.9" y2="76.3"/>
<animate xlink:href="#line1" attributeName="x2" from="65" to="180.9" dur="2s" class="ani" />
<line class="st3" id="line2" x1="237.6" y1="76.3" x2="338.6" y2="76.3"/>
<animate xlink:href="#line2" attributeName="x2" from="250" to="338.6" dur="2s" class="ani" />
<text x="200" y="80" class="wt1">10'</text>
</g>
<g>
<g>
<text x="368" y="70" class="wt1">5'</text>
</g>
<line class="st3" id="line3" x1="352.1" y1="76.9" x2="362.6" y2="70.8"/>
<animate xlink:href="#line3" attributeName="x2" from="351" to="362.6" dur="3s" class="ani" />
<animate xlink:href="#line3" attributeName="y2" from="77" to="70.8" dur="3s" class="ani" />
<line class="st3" id="line4" x1="387.7" y1="58" x2="396.6" y2="51.9"/>
<animate xlink:href="#line4" attributeName="x2" from="388" to="396.6" dur="3s" class="ani" />
<animate xlink:href="#line4" attributeName="y2" from="58" to="51.9" dur="3s" class="ani" />
</g>
<g>
<ellipse class="st4" id="elli1" cx="210.1" cy="344.8" rx="37.2" ry="4.5"/>
<animate xlink:href="#elli1" attributeName="rx" from="7.2" to="37.2" dur="3s" class="ani" />
<animate xlink:href="#elli1" attributeName="ry" from="0.2" to="4.5" dur="3s" class="ani" />
<g id="box1" transform="translate(0, 0)">
<polygon class="st5" points="230.8,307.5 213,307.5 213,307.9 213,314.1 207,314.1 207,307.5 189.2,307.5 188.9,345.4 231.2,345.4
"/>
<path class="st6" d="M207,307.3v-6.9c0-0.2,6-0.1,6-0.1v7.1h17.8l-8-7.1h-26.7l-7,7.1H207V307.3z"/>
<polygon class="st7" points="207,314.1 213,314.1 213,307.9 213,307.5 207,307.5 "/>
<path class="st8" d="M207,300.4v6.9v0.1h6v-7.1C213,300.4,207,300.2,207,300.4z"/>
<animateTransform xlink:href="#box1" attributeName="transform" type="translate" from="0 -70" to="0 0" dur="3s" class="ani" />
</g>
</g>
</svg>

You forgot to add a question style sheet. I restored the color values of the svg parts according to the figure.
Since all animations should start simultaneously at the click of a mouse, you can do without Javascript
To do this, add a launch command to each animation begin="Layer_1.click"
.container {
width:75%;
height:75%;
}
.st0 {fill:#C8C8C8;}
.st1 {fill:#E7E7E7;}
.st2 {fill:#6A6A6A;}
.st3 {stroke:#F6C44A;}
.st4 {fill:#323232;}
.st5 {fill:#CB9751;}
.st6 {fill:#E0B268;}
.st7 {fill:#C8A066;}
.st8 {fill:#E3C084;}
<div class="container">
<?xml version="1.0" encoding="utf-8"?>
<!-- Generator: Adobe Illustrator 21.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0) -->
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 425 386" style="enable-background:new 0 0 425 386;" xml:space="preserve">
<polygon class="st0" points="356.4,330 399.3,370.8 399.3,82.5 357.3,106.5 "/>
<polygon class="st1" points="63.8,105 63.8,329.3 357.3,329.3 357.3,106.5 "/>
<polygon class="st2" points="21.8,369 62.5,329.3 357.3,329.3 399.3,370.8 20.9,370.8 "/>
<polygon class="st0" points="63.8,329.2 20.9,370.8 20.9,82.5 63.8,105 "/>
<g>
<line class="st3" id="line1" x1="65.2" y1="76.3" x2="180.9" y2="76.3"/>
<animate xlink:href="#line1" attributeName="x2" from="65" to="180.9" begin="Layer_1.click" dur="2s" class="ani" />
<line class="st3" id="line2" x1="237.6" y1="76.3" x2="338.6" y2="76.3"/>
<animate xlink:href="#line2" attributeName="x2" from="250" to="338.6" begin="Layer_1.click" dur="2s" class="ani" />
<text x="200" y="80" class="wt1">10'</text>
</g>
<g>
<g>
<text x="368" y="70" class="wt1">5'</text>
</g>
<line class="st3" id="line3" x1="352.1" y1="76.9" x2="362.6" y2="70.8"/>
<animate xlink:href="#line3" attributeName="x2" from="351" to="362.6" begin="Layer_1.click" dur="3s" class="ani" />
<animate xlink:href="#line3" attributeName="y2" from="77" to="70.8" begin="Layer_1.click" dur="3s" class="ani" />
<line class="st3" id="line4" x1="387.7" y1="58" x2="396.6" y2="51.9"/>
<animate xlink:href="#line4" attributeName="x2" from="388" to="396.6" begin="Layer_1.click" dur="3s" class="ani" />
<animate xlink:href="#line4" attributeName="y2" from="58" to="51.9" begin="Layer_1.click" dur="3s" class="ani" />
</g>
<g>
<ellipse class="st4" id="elli1" cx="210.1" cy="344.8" rx="37.2" ry="4.5"/>
<animate xlink:href="#elli1" attributeName="rx" from="7.2" to="37.2" begin="Layer_1.click" dur="3s" class="ani" />
<animate xlink:href="#elli1" attributeName="ry" from="0.2" to="4.5" begin="Layer_1.click" dur="3s" class="ani" />
<g id="box1" transform="translate(0, 0)">
<polygon class="st5" points="230.8,307.5 213,307.5 213,307.9 213,314.1 207,314.1 207,307.5 189.2,307.5 188.9,345.4 231.2,345.4
"/>
<path class="st6" d="M207,307.3v-6.9c0-0.2,6-0.1,6-0.1v7.1h17.8l-8-7.1h-26.7l-7,7.1H207V307.3z"/>
<polygon class="st7" points="207,314.1 213,314.1 213,307.9 213,307.5 207,307.5 "/>
<path class="st8" d="M207,300.4v6.9v0.1h6v-7.1C213,300.4,207,300.2,207,300.4z"/>
<animateTransform xlink:href="#box1" attributeName="transform" type="translate" from="0 -70" to="0 0" begin="Layer_1.click" dur="3s" class="ani" />
</g>
</g>
</svg>
</div>

How to center an SVG element based on another element using js?

I made an SVG face and want to center each pupil in their respective eye.
I tried doing this by getting the center of the eye using getBoundingClientRect(). However when I set the position of the pupil this way it didn't work as expected (it did not center, and changes location based on size of page).
I'm guessing getBoundingClientRect() is related to a global position and the cx, cy attributes are local, but it's not clear to me what the attributes are local to or how I would fix it
Any ideas why this doesn't work and what approach might fix it?
Code
// Center the pupil in the eye. Side param is "left" or "right"
function center_pupil(side) {
let eye = document.querySelector(`#${side}-eye`).getBoundingClientRect()
let pupil = document.querySelector(`#${side}-pupil`)
let pupil_radius = pupil.getAttribute("r")
pupil.setAttribute("cx", eye.left + eye.width / 2 - pupil_radius)
pupil.setAttribute("cy", eye.top + eye.height / 2 - pupil_radius)
}
center_pupil("left")
center_pupil("right")
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 645.72 579.45">
<defs>
<clipPath id="clip-path" transform="translate(-114.91 -242.55)">
<path d="M544,377s9-21,54-25c0,0,114-7,150,25s-43,86-43,86-33.77,18.6-79.06,11.62C615.11,473,587.67,468.87,563,448c-10.53-8.91-25.76-21.79-27-42C535.2,393.05,540.49,382.61,544,377Z"
fill="none" />
</clipPath>
<clipPath id="clip-path-2" transform="translate(-114.91 -242.55)">
<path d="M117.5,397.5a38.69,38.69,0,0,1,8-11c6.89-6.57,14.55-8.78,19-10,32.47-8.93,45-10,45-10,34.68-2.95,53.54-4.56,81-1,33.83,4.38,50.79,6.54,61,21,13.58,19.24,5,45.13,4,48-6.94,20.08-23.19,30.46-35,38a106,106,0,0,1-29.07,12.82,108,108,0,0,1-39.93,3.18c-4.63.72-54.1,7.55-88.32-28.91C120.39,435.31,117.91,406.25,117.5,397.5Z"
fill="none" />
</clipPath>
</defs>
<title>face</title>
<g id="eyes">
<g id="right-eye">
<path d="M540.89,375.37A28.23,28.23,0,0,1,548.4,367a24,24,0,0,1,2.19-1.6c.76-.5,1.5-1,2.26-1.48,1.56-.86,3.07-1.81,4.67-2.55s3.14-1.57,4.76-2.23c.8-.34,1.6-.69,2.39-1.06l2.42-.94c.81-.31,1.61-.65,2.42-1s1.64-.56,2.46-.85l2.46-.81a25.18,25.18,0,0,1,2.49-.73c1.68-.43,3.34-.91,5-1.36s3.38-.71,5.07-1.07l2.54-.55,2.56-.41,5.14-.82c1.81-.26,3.45-.36,5.17-.53l5.12-.43q5.12-.4,10.23-.65a289.41,289.41,0,0,1,41,.71c6.82.65,13.62,1.57,20.39,2.63s13.51,2.37,20.23,3.71,13.41,2.9,20.15,4.54c1.69.38,3.36.86,5,1.36l2.51.73c.83.26,1.65.58,2.48.87l2.47.9c.82.3,1.61.71,2.42,1.05a49,49,0,0,1,4.78,2.33,52.84,52.84,0,0,1,4.63,2.72l2.26,1.48c.75.49,1.44,1.12,2.16,1.68l2.12,1.72c.67.65,1.37,1.27,2,2a30,30,0,0,1,3.57,4.42c.57.78,1,1.65,1.5,2.47s.88,1.73,1.21,2.64a25.41,25.41,0,0,1,1.57,5.59,29.78,29.78,0,0,1-.37,11.31c-4.58,14.09-13,25.18-22.33,35.35a178.89,178.89,0,0,1-14.84,14.31q-3.88,3.39-8,6.53c-2.72,2.11-5.44,4.15-8.32,6.15l-.11.08-.1.05c-2.33,1.23-4.54,2.18-6.86,3.13s-4.62,1.77-7,2.58c-4.68,1.57-9.43,2.87-14.23,4a151.83,151.83,0,0,1-29.28,3.67c-2.46,0-4.93.12-7.39.07l-7.41-.31-7.38-.71c-2.46-.23-4.85-.58-7.3-.93a131.55,131.55,0,0,1-28.88-7.35,114.07,114.07,0,0,1-13.69-6.28c-2.25-1.13-4.38-2.49-6.55-3.78-1.08-.65-2.09-1.41-3.14-2.11s-2.12-1.4-3.1-2.19a143.74,143.74,0,0,1-11.34-9.74,83.58,83.58,0,0,1-10.05-11.51A57.13,57.13,0,0,1,535.46,420a53.51,53.51,0,0,1-2.89-15.38,48.4,48.4,0,0,1,2-15.44,50,50,0,0,1,2.7-7.28c.54-1.17,1.12-2.32,1.76-3.44.31-.56.64-1.11,1-1.65S540.59,375.83,540.89,375.37Zm6.22,3.26c-.75,1.3-1.25,2.21-1.77,3.23s-1,2-1.52,3a56.3,56.3,0,0,0-2.49,6.29,41.51,41.51,0,0,0-2,13.2,34.3,34.3,0,0,0,2.84,12.95,45.72,45.72,0,0,0,7.15,11.32,91.37,91.37,0,0,0,9.77,9.7c3.46,3.07,7.29,6.18,10.83,9a112.56,112.56,0,0,0,23.73,14.54,121.21,121.21,0,0,0,13.15,5,135,135,0,0,0,13.72,3.63c2.31.47,4.7,1,7,1.32s4.69.73,7,1l7.1.56c2.37.13,4.75.12,7.13.18a128.42,128.42,0,0,0,28.29-3.39,135,135,0,0,0,13.69-4c2.23-.81,4.46-1.64,6.63-2.57s4.39-1.91,6.33-3l-.21.13c5.43-3.8,10.71-8.06,15.86-12.34s10.1-8.85,14.78-13.63a103.24,103.24,0,0,0,12.64-15.43,47.41,47.41,0,0,0,4.69-8.65,40.34,40.34,0,0,0,2.28-9.25,33.29,33.29,0,0,0,.35-4.54,22.19,22.19,0,0,0-.46-4.4,20.11,20.11,0,0,0-1.34-4.15c-.25-.67-.64-1.3-1-1.95s-.74-1.27-1.2-1.86a29.21,29.21,0,0,0-6.38-6.48c-.62-.47-1.2-1-1.86-1.44l-2-1.34a46,46,0,0,0-4.12-2.49c-11.39-6-24.05-11.23-37.37-13.24-13.25-2.37-26.77-3-40.22-3.48s-26.92-1-40.43-1.38l-10.13-.24-5.07-.07c-1.66,0-3.42,0-5,0a108.23,108.23,0,0,0-19.78,2.72,24.43,24.43,0,0,0-2.41.65l-2.39.72a43.68,43.68,0,0,0-4.71,1.63c-.77.32-1.55.6-2.3.94s-1.48.75-2.21,1.14-1.47.74-2.17,1.18l-2.06,1.35-1,.68c-.33.24-.64.51-1,.76l-1.9,1.53c-.6.54-1.18,1.11-1.76,1.65a20.72,20.72,0,0,0-1.67,1.71c-.54.58-1.07,1.17-1.54,1.78a21.79,21.79,0,0,0-1.41,1.83l-.66.93-.59.93c-.21.31-.34.62-.52.93-.09.15-.15.29-.22.43Z"
transform="translate(-114.91 -242.55)" />
</g>
<path d="M505,327" transform="translate(-114.91 -242.55)" />
<g id="left-eye">
<path d="M114.91,397a8.77,8.77,0,0,1,.41-1.29c.07-.21.14-.43.22-.65.15-.43.33-.85.52-1.27a23.67,23.67,0,0,1,1.3-2.43,33.63,33.63,0,0,1,3.35-4.38,39.68,39.68,0,0,1,8.37-7.14,45.38,45.38,0,0,1,9.88-4.59c3.45-1.11,6.75-1.8,10-2.64,6.64-1.59,13.29-3.11,20-4.49,3.35-.68,6.71-1.32,10.08-1.9,1.69-.29,3.38-.58,5.08-.84l2.56-.36,1.29-.16.66-.08.33,0,.17,0,.34,0h-.15l10-.79c3.36-.27,6.71-.48,10.05-1s6.66-1.26,10-1.68,6.74-.55,10.13-.72c6.78-.27,13.6-.4,20.41-.06s13.6.93,20.33,1.86,13.33,1.84,20,2.91a156,156,0,0,1,20.08,4.29c.83.26,1.66.55,2.49.83s1.65.56,2.47.91l2.45,1,2.4,1.19a37.88,37.88,0,0,1,8.79,6.29,39.43,39.43,0,0,1,6.43,8.62,19,19,0,0,1,1.21,2.38l1.11,2.43.86,2.52a18.46,18.46,0,0,1,.77,2.53,57.7,57.7,0,0,1,1.39,20.78,77.82,77.82,0,0,1-1.71,10.2c-.41,1.68-.84,3.35-1.38,5s-1.2,3.27-1.82,4.9a80.14,80.14,0,0,1-10.73,18l-.83,1-.87,1c-.6.64-1.17,1.32-1.79,1.94-1.24,1.23-2.49,2.46-3.82,3.59a93.34,93.34,0,0,1-8.31,6.24c-1.42.95-2.85,1.9-4.28,2.81s-2.82,1.81-4.32,2.74q-4.45,2.71-9.14,5a111.57,111.57,0,0,1-19.45,7.27,109.85,109.85,0,0,1-41.18,3l.81,0a96.63,96.63,0,0,1-10.64.84c-3.53.09-7.06,0-10.58-.18a118,118,0,0,1-20.88-3.16A104.42,104.42,0,0,1,170,482a97.9,97.9,0,0,1-18-11.15,94.11,94.11,0,0,1-26.21-32.74,104.55,104.55,0,0,1-7.36-19.73q-1.36-5.09-2.24-10.3c-.28-1.74-.57-3.48-.77-5.23-.12-.87-.2-1.75-.29-2.63l-.07-.66-.07-.86C114.94,398.15,114.92,397.55,114.91,397Zm5.18,1.08a7,7,0,0,1,.08.79l0,1.06c.05.83.09,1.67.17,2.5.11,1.68.31,3.34.51,5,.46,3.33,1.1,6.63,1.88,9.91.39,1.63.86,3.25,1.32,4.86s1,3.21,1.62,4.78c1.17,3.15,2.48,6.25,4,9.27a87.88,87.88,0,0,0,42.45,41.16,99.57,99.57,0,0,0,19,6.34,112.17,112.17,0,0,0,19.92,2.62c3.35.14,6.71.15,10.05,0a89,89,0,0,0,9.9-.94l.38-.06.43,0a105.31,105.31,0,0,0,19.53.1A110.47,110.47,0,0,0,270.55,482a104.55,104.55,0,0,0,18.21-6.92,96.58,96.58,0,0,0,8.52-4.71c1.36-.84,2.79-1.77,4.18-2.67s2.76-1.83,4.12-2.75c2.72-1.85,5.3-3.82,7.85-5.8s5-4,7.4-6.21a51.27,51.27,0,0,0,6.53-7.12,42.86,42.86,0,0,0,4.84-8.38,61.67,61.67,0,0,0,4.57-18.91,52.32,52.32,0,0,0-1.7-19.18,18.18,18.18,0,0,0-.76-2.26l-.84-2.22-1.06-2.12a16.05,16.05,0,0,0-1.13-2.08,35,35,0,0,0-5.82-7.29,34.22,34.22,0,0,0-7.68-5.19l-2.14-1-2.23-.86c-.73-.3-1.5-.55-2.27-.78s-1.53-.49-2.31-.71a160.49,160.49,0,0,0-19.39-3.74c-6.59-.93-13.26-1.73-19.92-2.52a264.5,264.5,0,0,0-39.7-1.74c-3.33.07-6.65.33-10,.27s-6.72-.28-10.08-.29a96.26,96.26,0,0,0-10.05.57l-10,.9h-.16l-2.26.33-2.48.41c-1.65.29-3.3.61-4.95.95-3.3.7-6.59,1.48-9.87,2.28-6.56,1.62-13.08,3.42-19.58,5.32-3.23,1-6.56,1.86-9.53,3a39,39,0,0,0-8.42,4.28,34.43,34.43,0,0,0-6.92,6.22,46.51,46.51,0,0,0-2.8,3.73l-1.37,1.92-.7,1-.37.48A.39.39,0,0,0,120.09,398Z"
transform="translate(-114.91 -242.55)" />
</g>
</g>
<g clip-path="url(#clip-path)">
<circle id="right-pupil" cx="532.09" cy="125.45" r="31" />
</g>
<g clip-path="url(#clip-path-2)">
<circle id="left-pupil" cx="116.59" cy="139.95" r="31" />
</g>
<g id="Layer_4" data-name="Layer 4">
<path d="M505,264s120-29,194-10" transform="translate(-114.91 -242.55)" fill="none" stroke="#000"
stroke-miterlimit="10" stroke-width="10" />
<path d="M154,280s116-27,179,0" transform="translate(-114.91 -242.55)" fill="none" stroke="#000"
stroke-miterlimit="10" stroke-width="10" />
<path d="M390,401c9.15,143.49,6.63,190.63,2,205,0,0-6.53,20.28-2,41a35.35,35.35,0,0,0,4,10s1.3,2.14,8,10"
transform="translate(-114.91 -242.55)" fill="none" stroke="#000" stroke-miterlimit="10"
stroke-width="10" />
<line x1="321.09" y1="415.45" x2="329.09" y2="424.45" fill="none" stroke="#000" stroke-miterlimit="10"
stroke-width="10" />
<path d="M363,774l146-4s-1,47-73,47S363,774,363,774Z" transform="translate(-114.91 -242.55)" fill="none"
stroke="#000" stroke-miterlimit="10" stroke-width="10" />
</g>
</svg>
What I'm currently seeing
Note: pupil location changes based on screen size

Changing SVG animation attributes of a specific path with javascript and jQuery

Making an SVG object that moves along a specific path, but would like to change the attributes of a specific circle on the path with javascript an jquery, specifically the animateMotion duration of each path, at the moment, the code does not seem to be working with buttons. I am not sure this JS snippet actually represents the changing of SVG attributes. The duration is already set in HTML, but how to amend the attributes of an already existing animation?
Should the whole animation be made with setting attributes from javascript and leaving the HTML empty?
function animate() {
var circle = $("circle1");
var circle2 = $("circle2");
circle.setAttributeNS("dur",2);
circle2.setAttributeNS("dur",4);
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<svg width="500" height="100">
<path fill="none" stroke="lightgrey"
d="M20,50 C20,-50 180,150 180,50 C180-50 20,150 20,50 z" />
<circle id="circle1" r="5" fill="brown">
<animateMotion dur="10s" repeatCount="indefinite"
path="M20,50 C20,-50 180,150 180,50 C180-50 20,150 20,50 z" />
</circle>
</svg>
<svg width="500" height="100">
<path fill="none" stroke="lightgrey"
d="M20,50 C20,-50 180,150 180,50 C180-50 20,150 20,50 z" />
<circle id="circle2" r="5" fill="red">
<animateMotion dur="10s" repeatCount="indefinite"
path="M20,50 C20,-50 180,150 180,50 C180-50 20,150 20,50 z" />
</circle>
</svg>
<br/>
<input type="button" value="Change duration" onclick="animate();">

Place svg element in specific position direction

I would place arrows ( subways) over circles element (stations).
Arrows could have two opposed directions, they should match the paths direction.
Actually I place my arrow on stations.
I have some issues at this level:
Arrows are not centered on stations position.
I can't figure how to set the direction of the arrow.
I have the possibility to set data on every station svg element statically if that could help to determine the direction in js code but I don't have an idea what kind of data to add.
So my problem is how to set arrows with the right angle depending on the paths angle, and also be able to choose the inverted angle
let rect = document.querySelectorAll('#stops > g');
rect.forEach(elm=> {
let thisCircle = elm.querySelector('circle');
const g = document.createElementNS('http://www.w3.org/2000/svg', 'g');
let cx = thisCircle.getAttribute('cx');
let cy = thisCircle.getAttribute('cy');
let text = document.createElementNS('http://www.w3.org/2000/svg', 'text');
text.textContent = '⯈';
text
g.setAttribute('transform', `translate(${cx},${cy})`);
g.appendChild(text);
let svg = document.getElementById("Calque_1");
svg.appendChild(g)
})
<svg id="Calque_1" data-name="Calque 1" xmlns="http://www.w3.org/2000/svg" width="900px" height="900px" viewBox="0 0 775.43 469.98">
<defs>
<style>.cls-1{fill:none;stroke-width:5px;}.cls-1,.cls-2{stroke:#a15256;}.cls-2{fill:#fff;}.cls-3{isolation:isolate;font-size:42.79px;font-family:ArialMT, Arial;}</style>
<marker id='mid' orient="auto" markerWidth='2' markerHeight='4' refX='0.1' refY='1'>
<!-- triangle pointing right (+x) -->
<path d='M0,0 V2 L1,1 Z' fill="orange"/>
</marker>
</defs>
<title>line</title>
<path id="path7" class="cls-1" d="M202,67.72,329.33,215.86" transform="translate(-200.1 -66.09)" />
<path id="path8" class="cls-1" d="M329.35,215.87,449,355" transform="translate(-200.1 -66.09)" />
<path id="path9" class="cls-1" d="M449,355c41.53,51.11,96.22,63.08,117.9,69.28" transform="translate(-200.1 -66.09)" />
<path id="path10" class="cls-1" d="M566.86,424.29C655.43,460.48,977.38,391.48,973,536" transform="translate(-200.1 -66.09)" />
<g id="stops">
<g id="g3670">
<circle class="cls-2" cx="129.24" cy="149.78" r="5.58" />
<text id="text3668" class="cls-3" transform="translate(140.84 114.12)">Station1</text>
</g>
<g id="g3700">
<circle class="cls-2" cx="248.91" cy="288.93" r="5.58" />
<text id="text3698" class="cls-3" transform="translate(284.5 239)">Station2</text>
</g>
<g id="g3750">
<circle class="cls-2" cx="366.75" cy="358.2" r="5.58" />
<text id="text3748" class="cls-3" transform="translate(134.96 379.59)">Station3</text>
</g>
</g>
</svg>
Angular stackblitz version

After a changing a few comments the OP is asking:
How will you use the marker ? ( the marler in the code was for placing arrows on the path when the a subway still in progress but for arrows in top of stations I don't see how to use it)
This is a way of doing it. You can change the value of the refX attribute to move it where you need it to be
path{marker-end:url(#mid)}
<svg id="Calque_1" viewBox="0 0 800 500">
<defs>
<style>.cls-1{fill:none;stroke-width:5px;}.cls-1,.cls-2{stroke:#a15256;}.cls-2{fill:#fff;}.cls-3{isolation:isolate;font-size:42.79px;font-family:ArialMT, Arial;}</style>
<marker id='mid' orient="auto" markerWidth='10' markerHeight='20' refX='6' refY='5'>
<!-- triangle pointing right (+x) -->
<path d='M0,0 V10 L5,5 Z' fill="orange"/>
</marker>
</defs>
<title>line</title>
<path id="path7" class="cls-1" d="M202,67.72,329.33,215.86" transform="translate(-200.1 -66.09)" />
<path id="path8" class="cls-1" d="M329.35,215.87,449,355" transform="translate(-200.1 -66.09)" />
<path id="path9" class="cls-1" d="M449,355c41.53,51.11,96.22,63.08,117.9,69.28" transform="translate(-200.1 -66.09)" />
<path id="path10" class="cls-1" d="M566.86,424.29C655.43,460.48,977.38,391.48,973,536" transform="translate(-200.1 -66.09)" />
<g id="stops">
<g id="g3670">
<circle class="cls-2" cx="129.24" cy="149.78" r="5.58" />
<text id="text3668" class="cls-3" transform="translate(140.84 114.12)">Station1</text>
</g>
<g id="g3700">
<circle class="cls-2" cx="248.91" cy="288.93" r="5.58" />
<text id="text3698" class="cls-3" transform="translate(284.5 239)">Station2</text>
</g>
<g id="g3750">
<circle class="cls-2" cx="366.75" cy="358.2" r="5.58" />
<text id="text3748" class="cls-3" transform="translate(134.96 379.59)">Station3</text>
</g>
</g>
</svg>
UPDATE
The OP is commenting:
How will you use the marker ? ( the marler in the code was for placing arrows on the path when the a subway still in progress but for arrows in top of stations I don't see how to use it)
In this case I would use marker-start and I've changed the refX="2
path:not(:first-of-type){marker-start:url(#mid)}
<svg id="Calque_1" viewBox="0 0 800 500">
<defs>
<style>.cls-1{fill:none;stroke-width:5px;}.cls-1,.cls-2{stroke:#a15256;}.cls-2{fill:#fff;}.cls-3{isolation:isolate;font-size:42.79px;font-family:ArialMT, Arial;}</style>
<marker id='mid' orient="auto" markerWidth='10' markerHeight='20' refX='2' refY='5'>
<!-- triangle pointing right (+x) -->
<path d='M0,0 V10 L5,5 Z' fill="orange"/>
</marker>
</defs>
<title>line</title>
<path id="path7" class="cls-1" d="M202,67.72,329.33,215.86" transform="translate(-200.1 -66.09)" />
<path id="path8" class="cls-1" d="M329.35,215.87,449,355" transform="translate(-200.1 -66.09)" />
<path id="path9" class="cls-1" d="M449,355c41.53,51.11,96.22,63.08,117.9,69.28" transform="translate(-200.1 -66.09)" />
<path id="path10" class="cls-1" d="M566.86,424.29C655.43,460.48,977.38,391.48,973,536" transform="translate(-200.1 -66.09)" />
<g id="stops">
<g id="g3670">
<circle class="cls-2" cx="129.24" cy="149.78" r="5.58" />
<text id="text3668" class="cls-3" transform="translate(140.84 114.12)">Station1</text>
</g>
<g id="g3700">
<circle class="cls-2" cx="248.91" cy="288.93" r="5.58" />
<text id="text3698" class="cls-3" transform="translate(284.5 239)">Station2</text>
</g>
<g id="g3750">
<circle class="cls-2" cx="366.75" cy="358.2" r="5.58" />
<text id="text3748" class="cls-3" transform="translate(134.96 379.59)">Station3</text>
</g>
</g>
</svg>
UPDATE
The OP is commenting:
I should set marker from JS because it depends on station. not all stations have a marker
You can use a class for the path like this:
.withMarker + path{marker-start:url(#mid)}
<svg id="Calque_1" viewBox="0 0 800 500">
<defs>
<style>.cls-1{fill:none;stroke-width:5px;}.cls-1,.cls-2{stroke:#a15256;}.cls-2{fill:#fff;}.cls-3{isolation:isolate;font-size:42.79px;font-family:ArialMT, Arial;}</style>
<marker id='mid' orient="auto" markerWidth='10' markerHeight='20' refX='2' refY='5'>
<!-- triangle pointing right (+x) -->
<path d='M0,0 V10 L5,5 Z' fill="orange"/>
</marker>
</defs>
<title>line</title>
<path id="path7" class="cls-1 withMarker" d="M202,67.72,329.33,215.86" transform="translate(-200.1 -66.09)" />
<path id="path8" class="cls-1" d="M329.35,215.87,449,355" transform="translate(-200.1 -66.09)" />
<path id="path9" class="cls-1 withMarker" d="M449,355c41.53,51.11,96.22,63.08,117.9,69.28" transform="translate(-200.1 -66.09)" />
<path id="path10" class="cls-1" d="M566.86,424.29C655.43,460.48,977.38,391.48,973,536" transform="translate(-200.1 -66.09)" />
<g id="stops">
<g id="g3670">
<circle class="cls-2" cx="129.24" cy="149.78" r="5.58" />
<text id="text3668" class="cls-3" transform="translate(140.84 114.12)">Station1</text>
</g>
<g id="g3700">
<circle class="cls-2" cx="248.91" cy="288.93" r="5.58" />
<text id="text3698" class="cls-3" transform="translate(284.5 239)">Station2</text>
</g>
<g id="g3750">
<circle class="cls-2" cx="366.75" cy="358.2" r="5.58" />
<text id="text3748" class="cls-3" transform="translate(134.96 379.59)">Station3</text>
</g>
</g>
</svg>
You'll have to keep in mind that is a marker-start.