JSON "markup" to ESC/POS

thermalparser.js

exports.parseToControlCommands = function (ob) {
    let ns = "";
    ob.input.forEach(function (t, number, ts) {
        if (typeof(t) === "string") {
            ns = ns.concat(t)
        } else {
            switch (t.command) {
                case "tab":
                    ns = ns.concat("\x09");
                    break;
                case "lineFeed":
                    if (!t.hasOwnProperty("value")) {
                        ns = ns.concat("\x0a");
                        break;
                    }
                    if (!(t.value >= 0 && t.value <= 255)) {
                        throw new Error("The tag's value should be between 0 and 255.");
                    }
                    ns = ns.concat("\x1b\x64").concat(String.fromCharCode(t.value));
                    break;
                case "setRightMargin":
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A setRightMargin tag has no value.");
                    }
                    if (!(t.value >= 0 && t.value <= 255)) {
                        throw new Error("The tag's value should be between 0 and 255.");
                    }
                    ns = ns.concat("\x1b\x20").concat(String.fromCharCode(t.value));
                    break;
                case "underline":
                    let ul;
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("An underline tag has no value.");
                    }

                    if (typeof(t.value) === "string") {
                        if (t.value !== "double") throw new Error("The tag's value should be either true, false or \"double\".");
                        ul = 2;
                    }
                    if (typeof(t.value) === "boolean") ul = t.value ? 1 : 0;
                    ns = ns.concat("\x1b\x2d").concat(String.fromCharCode(ul));
                    break;
                case "lineSpacing":
                    let ls;
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A lineSpacing tag has no value.");
                    }

                    if (typeof(t.value) === "string") {
                        if (t.value !== "default") throw new Error("The tag's value should be either a number between 0 and 255, or \"default\".");
                        ls = 2;
                    }
                    if (typeof(t.value) === "number") {
                        if (!(t.value >= 0 && t.value <= 255)) {
                            throw new Error("The tag's value should be between 0 and 255.");
                        }
                        ls = 1
                    }
                    ns = ls === 2 ? ns.concat("\x1b\x32") : ns.concat("\x1b\x33").concat(String.fromCharCode(t.value));
                    break;
                case "reset":
                    ns = ns.concat("\x1b\x40");
                    break;
                case "bold":
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A bold tag has no value.");
                    }
                    if (typeof(t.value) !== "boolean") {
                        throw new Error("The tag's value should be true or false.");
                    }
                    ns = ns.concat("\x1b\x45").concat(String.fromCharCode(t.value ? 1 : 0));
                    break;
                case "justify":
                    let j;
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A justify tag has no value.");
                    }
                    if (typeof(t.value) !== "string") {
                        throw new Error("The tag's value should be \"left\", \"center\", or \"right\".");
                    }
                    switch (t.value) {
                        case "left":
                            j=0;
                            break;
                        case "center":
                            j=1;
                            break;
                        case "right":
                            j=2;
                            break;
                        default:
                            throw new Error("The tag's value should be \"left\", \"center\", or \"right\".");
                    }
                    ns = ns.concat("\x1b\x61").concat(String.fromCharCode(j));
                    break;
                case "setFontSize":
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A setFontSize tag has no value.");
                    }
                    if (typeof(t.value) !== "object") {
                        throw new Error("The tag's value should be an object containing the \"h\" and \"v\" properties.");
                    }
                    ns = ns.concat("\x1d\x21").concat(String.fromCharCode(parseInt(`0x${t.value.h}${t.value.v}`)));
                    break;
                case "reverseVideo":
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A bold reverseVideo has no value.");
                    }
                    if (typeof(t.value) !== "boolean") {
                        throw new Error("The tag's value should be true or false.");
                    }
                    ns = ns.concat("\x1d\x42").concat(String.fromCharCode(t.value ? 1 : 0));
                    break;
                case "setLeftMargin":
                    if (!t.hasOwnProperty("value")) {
                        throw new Error("A setLeftMargin tag has no value.");
                    }
                    if (!(t.value >= 0 && t.value <= 255)) {
                        throw new Error("The tag's value should be between 0 and 255.");
                    }
                    ns = ns.concat("\x1d\x4c").concat(String.fromCharCode(t.value));
                    break;
                case "cutPaper":
                    ns = ns.concat("\x1d\x56\x01");
                    break;
            }

        }

    });
    return Buffer.from(ns, 'latin1');

};