function getHighest(arr, period) {
    if (arr.length == 0 || arr.length - period < 0) {
        return null 
    }
    var beginIndex = arr.length - period
    var ret = arr[beginIndex].High
    for (var i = 0 ; i < arr.length - 1 ; i++) {
        if (arr[i + 1].High > ret) {
            ret = arr[i + 1].High
        }
    }
    return ret
}

function getLowest(arr, period) {
    if (arr.length == 0 || arr.length - period < 0) {
        return null 
    }
    var beginIndex = arr.length - period
    var ret = arr[beginIndex].Low
    for (var i = 0 ; i < arr.length - 1 ; i++) {
        if (arr[i + 1].Low < ret) {
            ret = arr[i + 1].Low
        }
    }
    return ret
}

function calcFisher(records, ratio, period) {
    var preFish = 0 
    var preX = 0
    var arrFish = []
    // 当K线长度不足，不满足周期时
    if (records.length < period) {
        for (var i = 0 ; i < records.length ; i++) {
            arrFish.push(0)
        }
        return arrFish
    }

    // 遍历K线
    for (var i = 0 ; i < records.length ; i++) {
        var fish = 0
        var x = 0
        var bar = records[i]
        var mid = (bar.High + bar.Low) / 2
        // 当前BAR不足period计算时
        if (i < period - 1) {
            fish = 0
            preFish = 0
            arrFish.push(fish)
            continue
        }

        // 计算周期内最高价和最低价
        var bars = []
        for (var j = 0 ; j <= i ; j++) {
            bars.push(records[j])
        }
        var lowestLow = getLowest(bars, period)
        var highestHigh = getHighest(bars, period)               
        
        // 价变参数
        x = ratio * 2 * ((mid - lowestLow) / (highestHigh - lowestLow) - 0.5) + (1 - ratio) * preX
        if (x > 0.99) {
            x = 0.999
        } else if (x < -0.99) {
            x = -0.999
        }
        preX = x 
        fish = 0.5 * Math.log((1 + x) / (1 - x)) + 0.5 * preFish
        preFish = fish
        arrFish.push(fish)
    }
    return arrFish
}

X.X！