基于JS和SVG的超酷下雨特效

这是一款基于JS和SVG的超酷下雨特效。该特效通过在js代码构建SVG线条，并使线条运动起来，形成下雨效果，非常炫酷。

function rain(el = document.body, params) {
            if (!el) {
                console.error('Must have element to populate the rain!');
                return;
            }
            const defaultProperties = {
                colors: 'default',
                drop: window.innerHeight,
                fadeout: true,
                raindrops: 400,
                speed: 2000,
                splashes: true,
                spread: window.innerWidth
            };
 
 
            // properties passed in from user onto the defaults
            const c = Object.assign(defaultProperties, params);
 
            const randInt = (min, max) => {
                return Math.floor(Math.random() * (max - min + 1)) + min;
            };
            let hh = window.innerHeight;
            let ww = window.innerWidth;
            let raindrops = '';
            let rainsplashes = '';
            if (!c.flakes || Number.isNaN(c.flakes * 1)) {
                c.flakes = 250;
            }
            for (let i = 0; i < c.flakes; i++) {
                if (window.CP.shouldStopExecution(0)) break;
                let dur = c.speed;
                raindrops += `<g transform="translate(${randInt(0, ww)} -26) scale(1.${randInt(0, 3)})">
        <rect id="snowflake${i}" fill="rgba(240, 240, 255, ${randInt(1, 10) / 10})" x="0" y="0" rx="1" height="${randInt(4, 10)}" width="${randInt(3, 5) / 10}" filter="url(#blur${randInt(1, 2)})">
        </rect>
    </g>
    <animateMotion xlink:href="#snowflake${i}" dur="${dur}ms" begin="-${randInt(0, 100) / 10}s" repeatCount="indefinite">
        <mpath xlink:href="#motionPath${randInt(1, 2)}" />
    </animateMotion>`;
                // animated circle splashes
                if (c.splashes) {
                    if (randInt(0, 1) == 1) {
                        let randTiming = -randInt(0, 10) / 10;
                        rainsplashes += `<ellipse stroke="rgba(240, 240, 255, ${randInt(1, 4) / 10})" stroke-width="1" fill="none" cx="${randInt(0, ww)}" cy="${randInt(hh, hh / 1.2)}" rx="5" ry="3">
            <animate
                 attributeType="XML" attributeName="stroke-width"
                 dur="1s" values="0; 0.7; 0"
                 repeatCount="indefinite" begin="${randTiming}" />
            <animate
                 attributeType="XML" attributeName="rx"
                 dur="${c.speed / 2}ms" values="0; ${randInt(5, 9)}"
                 repeatCount="indefinite" additive="sum" begin="${randTiming}" />
            <animate
                 attributeType="XML" attributeName="ry"
                 dur="${c.speed / 2}ms" values="0; ${randInt(1, 2)}"
                 repeatCount="indefinite" additive="sum" begin="${randTiming}" />
                 <!--
            <animate
                 attributeType="XML" attributeName="cx"
                 dur="${c.speed / 2}ms" values="${randInt(0, ww)}; ${randInt(0, ww)}"
                 repeatCount="indefinite" additive="sum" begin="${randTiming}" />
                 -->
            </ellipse>`;
                    }
                }
            }
            window.CP.exitedLoop(0);
 
            let svg = `<svg id="snowverlay" viewbox="0 0 ${ww} ${hh}" height="${hh}" width="${ww}" preserveAspectRatio="none" style="z-index:99999; user-select:none; pointer-events:none; top:50%;
    left:50%; position:fixed; transform:translate(-50%,-50%)">
    <filter id="blur1" x="-100%" y="-100%" width="300%" height="300%">
        <feGaussianBlur in="SourceGraphic" stdDeviation="1" />
    </filter>
    <filter id="blur2" x="-100%" y="-100%" width="300%" height="300%">
        <feGaussianBlur in="SourceGraphic" stdDeviation="2" />
    </filter>
    <path id="motionPath1" fill="none" stroke="none" d="M 0 -${hh * 0.1} V ${hh * 1.1}" />
    <path id="motionPath2" fill="none" stroke="none" d="M 0 -${hh * 0.1} V ${hh * 1.1}" />
    ${raindrops}
    ${rainsplashes}
</svg>`;
            //Make it a node to avoid the dangerous "document.body.innerHTML = svg"
            let wrapper = document.createElement("div");
            wrapper.innerHTML = svg;
            let doc = wrapper.firstChild;
            const element = document.getElementById("snowverlay");
            element?.remove();
            document.body.appendChild(doc);
        }
 
        window.onload = rain(document.body);
        window.onresize = rain;

代码参考：
https://codepen.io/leimapapa/details/OJZRWpr