SVG dashed line animation (draw and flow together) - animation

Question

I have to make svg animation with dashed line.
I want to draw a line along with the flow.
Or draw line first and if drawing is finish, start flow.
But I can only implement separately.
How can I animate it together?
Help please..
This is my code.
https://codepen.io/hyhong/pen/KKBpvKQ
.item1 .dashed {
stroke-dasharray: 10 7;
}
.item1 .path {
animation: draw 1.5s alternate linear forwards;
}
#keyframes draw {
from {
stroke-dashoffset: 364;
}
to {
stroke-dashoffset: 0;
}
}
.item2 .path {
stroke-dasharray: 10;
stroke-dashoffset: 100;
animation: flow 3s linear infinite;
}
#keyframes flow {
100% {
stroke-dashoffset: 0;
}
}
<!-- draw svg -->
<svg class="item1" width="700" height="700">
<defs>
<path
id="dashed" class="dashed"
d="M 280 270 L 470 410 L 410 460 L 450 490"
stroke-miterlimit="10"
fill="none"
stroke="white"
stroke-width="5"
></path>
<mask id="mask">
<use xlink:href="#dashed"/>
</mask>
</defs>
<path
class="path"
d="M 280 270 L 470 410 L 410 460 L 450 490"
mask="url(#mask)"
stroke-miterlimit="10"
fill="none"
stroke="#3835B9"
stroke-width="5"
stroke-dasharray="364"
stroke-dashoffet="364"
></path>
</svg>
<!-- flow svg -->
<svg class="item2" width="700" height="700">
<path
class="path"
d="M 280 270 L 470 410 L 410 460 L 450 490"
stroke-miterlimit="10"
fill="none"
stroke="#3835B9"
stroke-width="5"
></path>
</svg>

Answer 1

I don't get your question 100%. but SVG SMIL Animation can be used in a situation where you need to time the starting (and ending) of different animations using <animate>. So, here are three examples where I animate stroke-dashoffset.
In the first the animations are independent, the green just starts 2 seconds after the red. In the second example the green starts when the red ends. You can see that the begin attribute refer to the the id of the red. The same goes for the third example.
<p>Green begin 2s after red:</p>
<svg viewBox="0 0 250 10">
<path d="M 20 5 h 100" stroke="red" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate attributeName="stroke-dashoffset"
values="100;-100" dur="4s" fill="freeze"
repeatCount="1" />
</path>
<path d="M 120 5 h 100" stroke="green" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate attributeName="stroke-dashoffset"
values="100;0" dur="2s" fill="freeze"
repeatCount="1" begin="2s" />
</path>
</svg>
<p>Green begin when red ends:</p>
<svg viewBox="0 0 250 10">
<path d="M 20 5 h 100" stroke="red" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate id="a1" attributeName="stroke-dashoffset"
values="100;-100" dur="4s" fill="freeze"
repeatCount="1" />
</path>
<path d="M 120 5 h 100" stroke="green" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate attributeName="stroke-dashoffset"
values="100;0" dur="2s" fill="freeze"
repeatCount="1" begin="a1.end" />
</path>
</svg>
<p>Green begin 1s after red begin:</p>
<svg viewBox="0 0 250 10">
<path d="M 20 5 h 100" stroke="red" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate id="a2" attributeName="stroke-dashoffset"
values="100;-100" dur="4s" fill="freeze"
repeatCount="1" />
</path>
<path d="M 120 5 h 100" stroke="green" stroke-width="10"
stroke-dasharray="100" stroke-dashoffset="100" pathLenth="100">
<animate attributeName="stroke-dashoffset"
values="100;0" dur="2s" fill="freeze"
repeatCount="1" begin="a2.begin+1s" />
</path>
</svg>

Answer 2

You can use the values from the css in the SVG "animate" property. The CSS animation is looping the "stroke-dashoffset" values from 100 to 0. On the other hand it overrides the stroke-dasharray="10 7" to stroke-dasharray="10" without reason. So you can use the original "10 7" (10 pixel dash, 7 pixel gap) design, if you like to.
<svg width="250" height="250">
<path
d="M 30 10 L 220 150 L 160 200 L 200 230"
stroke-miterlimit="10"
fill="none"
stroke="#3835B9"
stroke-width="5"
stroke-dasharray="10"
stroke-dashoffset="1">
<animate
attributeName="stroke-dashoffset"
values="100;0"
dur="3s"
calcMode="linear"
repeatCount="indefinite" />
</path>
</svg>