Lerp curve by echart

lerp.js

var transition = 0.14 
var threshold = 0.001

var y = [], x = []
var current = 0.01
var target = 1

// Demo Curve
// Lerp Curve
var lx = Array.from(new Array(1000), (v, i) => i/1000)
var ly = lx.map((v, i) => {
    var x = v
    return x * x * x * (x * (x * 6 - 15) + 10)
})
// SmoothStep Curve (3rd-order equation)
var sx3 = Array.from(new Array(1000), (v, i) => i/1000)
var sy3 = sx3.map((v, i) => {
    var x = v
    return 1 - x * x * x * (x * (x * 6 - 15) + 10)
})
// SmoothStep Curve (2rd-order equation)
var sx2 = Array.from(new Array(1000), (v, i) => i/1000)
var sy2 = sx2.map((v, i) => {
    var x = v
    return 1 - x * x * (3 - 2 * x)
})

// Interpolation Curve
var interpolation = {
    lerp: (curr, target, transition) => {
        var x = target - curr
        return x * transition
    },
    smoothStep2: (curr, target) => {
        var x = (target - curr)/target
        return x * x * (3 - 2 * x)
    },
    smoothStep3: (curr, target) => {
        var x = (target - curr)/target
        return x * x * x * (x * (x * 6 - 15) + 10)
    }
}
function iterator() {
    var step = interpolation.lerp(current, target, transition)
    y.push(step)
    current += step
    if (target-current < threshold) {
        x = Array.from(new Array(y.length), (v, i) => i)
    } else {
        iterator()
    }
}
iterator()

// Render Curve
option = {
    xAxis: {
        type: 'category',
        data: x
    },
    yAxis: {
        type: 'value'
    },
    series: [{
        data: y,
        type: 'line',
        smooth: true
    }]
};