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HTML

            
              <!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <button id="replay">replay</button>
  <canvas id="canvas"></canvas>
</body>
</html>
!

CSS

            
              canvas{
  width:400px;
  heigth:400px;
}
!

JS

            
              const cos = Math.cos,
    acos = Math.acos,
    min = Math.min,
    max = Math.max,
    tau = 2 * Math.PI,
    crt = function (v) {
        if (v < 0) return -Math.pow(-v, 1 / 3);
        return Math.pow(v, 1 / 3);
    },
    sqrt = function (v) { return Math.sqrt(v); };
const canvas = document.getElementById("canvas")
const context = canvas.getContext("2d")
const canvasWidth = 1050
const canvasHeight = 1050
const cap = 50
const colNum = Math.ceil(canvasWidth / cap) - 1
const rowNum = Math.ceil(canvasHeight / cap) - 1
const initX = 50
const initY = 1000
const lineWidth = 4
let Grids = []
let cache = null
const points = [
    [0, 0],
    [75, 750],
    [875, 360],
    [1000, 1000]
].map((p) => [p[0] + initX, initY - p[1]])
let initPoint = points[0], x = 0, isEnded = false
const replay = document.getElementById("replay")
//
canvas.width = canvasWidth
canvas.height = canvasHeight
context.lineWidth = 10
context.fillStyle="white"
context.fillRect(0, 0, canvas.width, canvas.height)
//建立网格
function initGrid(cap, width, height, lineWidth) {
    const colNum = Math.ceil(width / cap) - 1
    const rowNum = Math.ceil(height / cap) - 1
    for (let i = 1; i <= colNum; i++) {
        Grids.push([[cap * i - lineWidth/4, 0, lineWidth/2, colNum * cap], [(i - 1) * cap, cap * i - lineWidth/2, colNum * cap + 5, "top", "center"]])
    }
    for (let i = 1; i <= rowNum; i++) {
        Grids.push([[initX, cap * i - lineWidth/2, rowNum * cap, lineWidth/2], [(rowNum - i) * cap, initX - 5, cap * i - lineWidth/4, "middle", "right"]])
    }
}
initGrid(cap, canvasWidth, canvasHeight, lineWidth);
function createGrid() {
    context.fillStyle = '#999';
    context.font = "24px Arial"
    Grids.forEach((grid) => {
        context.textAlign = grid[1][4]
        context.textBaseline = grid[1][3]
        context.fillRect(grid[0][0], grid[0][1], grid[0][2], grid[0][3])
        context.save()
        context.fillText(grid[1][0], grid[1][1], grid[1][2]);
        context.restore()
    })
}
createGrid()
replay.addEventListener("click", () => {
    if (isEnded) {
        initPoint = points[0]
        isEnded = false;
        x = 0;
        context.fillStyle="white"
        context.fillRect(0, 0, canvas.width, canvas.height)
        createGrid()
        animation2()
    }
})
animation2()
function animation2() {
    if (x > 1040) { isEnded = true; return }
    let t = cardano(points, x)[0] || 0
    //曲线
    context.strokeStyle = "#d2fe9e"
    let initPoint2 = drawCubicBezierCurzeByX(points, t)
    drawLine(initPoint[0], initPoint[1],initPoint2[0], initPoint2[1])
    //进度曲线
    context.save()
    context.strokeStyle = "#9eccfe"
    drawLine(initX,initPoint[1],initX,initPoint2[1])
    drawLine(initPoint[0],initY,initPoint2[0], initY)
    
    initPoint=initPoint2
    drawCubicBezierCurzeHelper(points, initPoint[2], [initPoint[0], initPoint[1]])
    let img = new Image();
    img.src = cache
    img.onload = function () {
        context.drawImage(img, 0, 0, canvas.width, canvas.height)
        window.requestAnimationFrame(() => {
            x += 10
            animation2()
        })
    }
}

function drawCubicBezierCurzeHelper(points, t, circle) {
    let [p0, p1, p2, p3] = points
    let a = linearBezierCurze(...p0, ...p1)(t)
    let b = linearBezierCurze(...p1, ...p2)(t)
    let c = linearBezierCurze(...p2, ...p3)(t)
    let e = linearBezierCurze(...a, ...b)(t)
    let f = linearBezierCurze(...b, ...c)(t)
    context.save()
    context.strokeStyle = "gray"
    points.reduce((p, c) => {
        drawLine(...p,...c)
        return c
    })
    cache = canvas.toDataURL("image/jpeg",1);
    context.strokeStyle = "orange"
    drawLine(...a,...b)
    drawLine(...b,...c)
    context.strokeStyle = "#f5147f"
    drawLine(...e,...f)
    context.restore()
}
function drawCubicBezierCurzeByX(points, x) {
    let [p0, p1, p2, p3] = points,
        [x0, y0] = p0,
        [x1, y1] = p1,
        [x2, y2] = p2,
        [x3, y3] = p3
    let a = -(x0 - 3 * x1 + 3 * x2 - x3),
        b = 3 * (x0 - 2 * x1 + x2),
        c = -3 * (x0 - x1),
        d = x0 - x
    tri = 18 * a * b * c * d - 4 * b * b * b * d + b * b * c * c - 4 * a * c * c * c - 27 * a * a * d * d
    tri0 = b * b - 3 * a * c
    tri1 = 2 * b * b * b - 9 * a * b * c + 27 * a * a * d
    tmp = -27 * a * a * tri//==Math.pow(tri1,2)-4*Math.pow(tri0,3)
    let C1 = (tri1 - Math.sqrt(tmp)) / 2, C2 = (tri1 + Math.sqrt(tmp)) / 2
    C1 = C1 < 0 ? -Math.pow(-C1, 1 / 3) : Math.pow(C1, 1 / 3)
    C2 = C2 < 0 ? -Math.pow(-C2, 1 / 3) : Math.pow(C2, 1 / 3)
    let t=x
    return [
        Math.pow(1 - t, 3) * x0 + 3 * Math.pow(1 - t, 2) * t * x1 + 3 * t * t * (1 - t) * x2 + Math.pow(t, 3) * x3,
        Math.pow(1 - t, 3) * y0 + 3 * Math.pow(1 - t, 2) * t * y1 + 3 * t * t * (1 - t) * y2 + Math.pow(t, 3) * y3,
        t
    ]
}
function drawLine(x0,y0,x1,y1){
    context.beginPath();
    context.moveTo(x0, y0);
    context.lineTo(x1, y1);
    context.stroke()
    context.closePath();
}
function linearBezierCurze(a, b, c, d) {//(a,b),(c,d)
    let s1 = c - a, s2 = d - b
    return function (t) {
        return [
            s1 * t + a,
            s2 * t + b
        ]
    }
}
function cardano(points, x) {
    let [pt0, pt1, pt2, pt3] = points,
        [pa, y0] = pt0,
        [pb, y1] = pt1,
        [pc, y2] = pt2,
        [pd, y3] = pt3,
        d = (-pa + 3 * pb - 3 * pc + pd),
        a = (3 * pa - 6 * pb + 3 * pc) / d,
        b = (-3 * pa + 3 * pb) / d,
        c = (pa - x) / d,
        p = (3 * b - a * a) / 3,
        p3 = p / 3,
        q = (2 * a * a * a - 9 * a * b + 27 * c) / 27,
        q2 = q / 2,
        discriminant = q2 * q2 + p3 * p3 * p3,
        u1, v1, x1, x2, x3;
    if (discriminant < 0) {
        var mp3 = -p / 3,
            mp33 = mp3 * mp3 * mp3,
            r = sqrt(mp33),
            t = -q / (2 * r),
            cosphi = t < -1 ? -1 : t > 1 ? 1 : t,
            phi = acos(cosphi),
            crtr = crt(r),
            t1 = 2 * crtr;
        x1 = t1 * cos(phi / 3) - a / 3;
        x2 = t1 * cos((phi + tau) / 3) - a / 3;
        x3 = t1 * cos((phi + 2 * tau) / 3) - a / 3;
        return [x1, x2, x3].filter((xx) => xx >= 0 && xx <= 1);
    }

    else if (discriminant === 0) {
        u1 = q2 < 0 ? crt(-q2) : -crt(q2);
        x1 = 2 * u1 - a / 3;
        x2 = -u1 - a / 3;
      
        return [x1, x2].filter((xx) => xx >= 0 && xx <= 1);
    }else {
        var sd = sqrt(discriminant),
            tt = -q2 + sd;
        u1 = crt(-q2 + sd);
        v1 = crt(q2 + sd);
        x1 = u1 - v1 - a / 3;
        return [x1].filter((xx) => xx >= 0 && xx <= 1);
    }
}
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