Custom RSI with oversold and overbought

Custom Indicators
1

const predef = require("…/tools/predef");
const meta = require("…/tools/meta");
const EMA = require("…/tools/EMA");

class relativeStrengthIndex {
init() {
this.lossAverage = EMA(this.props.period);
this.gainAverage = EMA(this.props.period);
}

map(d, i, history) {
    const difference = i > 0 ? d.value() - history.prior()
        .value() : 0;
    const averageGain = this.gainAverage(Math.max(difference, 0));
    const averageLoss = Math.abs(this.lossAverage(Math.min(difference, 0)));

    let rsi = null;
    if (i >= this.props.period) {
        rsi = 100 - (100 / (1 + (averageGain / averageLoss)));
    }
    return {
        rsi,
        middle: 50,
        overbought: 90,
        oversold: 10
    };
}

filter(d) {
    return predef.filters.isNumber(d.rsi);
}

}

module.exports = {
name: “rsi”,
description: “Relative Strength Index”,
calculator: relativeStrengthIndex,
params: {
period: predef.paramSpecs.period(3)
},
plots: {
rsi: { title: “RSI” },
middle: { displayOnly: true },
overbought: { displayOnly: true },
oversold: { displayOnly: true }
},
tags: [predef.tags.Oscillators],
areaChoice: meta.AreaChoice.NEW,
schemeStyles: {
dark: {
rsi: predef.styles.plot("#ffe270"),
middle: predef.styles.plot({
color: “#7E838C”,
lineStyle: 3
}),
overbought: predef.styles.plot({
color: “#5DC74F”,
lineStyle: 3
}),
oversold: predef.styles.plot({
color: “#E52545”,
lineStyle: 3
})
}
}
};