prefix-si/index.js

SI, IEC, BS1852 compatible number formatter

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
var typescript_object_utils_1 = require("typescript-object-utils");
var standards = {
    si: {
        minPrefix: -8,
        prefixes: ["y", "z", "a", "f", "p", "n", "μ", "m", "", "k", "M", "G", "T", "P", "E", "Z", "Y"],
        base: 1000
    },
    iec: {
        minPrefix: 0,
        prefixes: ["", "Ki", "Mi", "Gi", "Ti", "Pi", "Ei", "Zi", "Yi"],
        base: 1024
    },
    bs1852_R: {
        minPrefix: 0,
        prefixes: ["R", "K", "M", "G", "T"],
        base: 1000
    },
    bs1852_F: {
        minPrefix: -4,
        prefixes: ["p", "n", "μ", "m", "F"],
        base: 1000
    }
};
var defaults = {
    binary: false,
    round: 2,
    spacer: "",
    decimalMark: "."
};
function prefix(value, unit, options) {
    options = typescript_object_utils_1.merge(defaults, options || {});
    var standard;
    if (options.bs1852) {
        if (unit === "R") {
            standard = standards.bs1852_R;
        }
        else if (unit === "F") {
            standard = standards.bs1852_F;
        }
        else {
            standard = standards.si;
        }
    }
    else {
        standard = options.binary ? standards.iec : standards.si;
    }
    var minPrefix = standard.minPrefix;
    var prefixes = standard.prefixes;
    var maxPrefix = prefixes.length + minPrefix - 1;
    var base = standard.base;
    var absValue = Math.abs(value);
    var exponent = absValue ? Math.floor(Math.log(absValue) / Math.log(base)) : 0;
    exponent = Math.min(maxPrefix, Math.max(minPrefix, exponent));
    var prefix = prefixes[exponent - minPrefix];
    var prefixBase = Math.pow(base, exponent);
    var val = value / prefixBase;
    var valString = String(val);
    unit = unit ? unit : "";
    if (options.fixed) {
        valString = val.toFixed(options.fixed);
    }
    else if (options.precision) {
        valString = val.toPrecision(options.precision);
    }
    else {
        var roundPow = Math.pow(10, +options.round);
        valString = String(Math.round(val * roundPow) / roundPow);
    }
    if (options.bs1852) {
        var parts = valString.split(".");
        if (parts.length == 2) {
            return (parts[0] == "0" ? "" : parts[0]) + (prefix ? prefix : (unit ? unit : options.decimalMark)) + (parts[1]);
        }
        else {
            return valString + (prefix ? prefix : unit) + (valString.length == 1 ? "0" : "");
        }
    }
    return valString.replace(".", options.decimalMark) + options.spacer + prefix + unit;
}
exports.prefix = prefix;