Metric Converter(Simple Conditions)

function metricConverter(input) {
    let distance = Number(input[0]);
    let inputMetric = input[1];
    let outputMetric = input[2];

    if (inputMetric == "m") {
        distance /= 1000;
    } else if (inputMetric == "cm") {
        distance /= 100000;
    } else if (inputMetric == "mm") {
        distance /= 1000000;
    } else if (inputMetric == "mi") {
        distance /= 0.621371192;
    } else if (inputMetric == "in") {
        distance /= 39370.0787;
    } else if (inputMetric == "ft") {
        distance /= 3280.8399;
    } else if (inputMetric == "yd") {
        distance /= 1093.6133;
    }

    if (outputMetric == "m") {
        distance *= 1000;
    } else if (outputMetric == "cm") {
        distance *= 100000;
    } else if (outputMetric == "mm") {
        distance *= 1000000;
    } else if (outputMetric == "mi") {
        distance *= 0.621371192;
    } else if (outputMetric == "in") {
        distance *= 39370.0787;
    } else if (outputMetric == "ft") {
        distance *= 3280.8399;
    } else if (outputMetric == "yd") {
        distance *= 1093.6133;
    }

    console.log(distance);
    return;
}

Решение с тернарен оператор:

function metricConverter(input) {
    let distance = Number(input[0]);
    let inputMetric = input[1];
    let outputMetric = input[2];

    distance /=
        inputMetric == "m" ? 1000 :
        inputMetric == "cm" ? 100000 :
        inputMetric == "mm" ? 1000000 :
        inputMetric == "mi" ? 0.621371192 :
        inputMetric == "in" ? 39370.0787 :
        inputMetric == "ft" ? 3280.8399 :
        inputMetric == "yd" ? 1093.6133 : 1;

    distance *=
        outputMetric == "m" ? 1000 :
        outputMetric == "cm" ? 100000 :
        outputMetric == "mm" ? 1000000 :
        outputMetric == "mi" ? 0.621371192 :
        outputMetric == "in" ? 39370.0787 :
        outputMetric == "ft" ? 3280.8399 :
        outputMetric == "yd" ? 1093.6133 : 1;

    console.log(distance);
    return;
}

Решение с речник:

function metricConverter(input) {
    let distance = Number(input[0]);
    let inputMetric = input[1];
    let outputMetric = input[2];

    let metricsToKM = {
        "km": 1,
        "m": 1000,
        "cm": 100000,
        "mm": 1000000,
        "mi": 0.621371192,
        "in": 39370.0787,
        "ft": 3280.8399,
        "yd": 1093.6133
    };

    console.log(distance / metricsToKM[inputMetric] * metricsToKM[outputMetric]);
    return;
}