NativeScript trace writer setup

howToUse.js

// in app.ts before application.start
import * as trace from "tns-core-modules/trace";
trace.setCategories(trace.categories.concat(
    // trace.categories.Layout, // add these two for detailed
    // trace.categories.ViewHierarchy, // add these two for detailed
    trace.categories.NativeLifecycle, // these two are for brief
    trace.categories.Navigation // these two are for brief
    ));
// trace.setCategories(trace.categories.All); // this option is extremely detailed
import { setupTimestampConsoleWriter } from "./shared/traceWriter";
setupTimestampConsoleWriter();
trace.enable();

traceWriter.js

"use strict";
exports.__esModule = true;
var trace = require("tns-core-modules/trace");
var StampedWriter = /** @class */ (function () {
    function StampedWriter() {
    }
    StampedWriter.prototype.write = function (message, category, type) {
        if (!console)
            return;
        var newTime = new Date();
        if (!this.startTime || (newTime.getTime() - this.lastCalledAt.getTime()) > 3000) {
            this.startTime = newTime;
        }
        this.lastCalledAt = newTime;
        var timeDiff = newTime.getTime() - this.startTime.getTime();
        var msgType = type || trace.messageType.log;
        var traceMessage = "time +" + timeDiff + " " + category + ": " + message;
        switch (msgType) {
            case trace.messageType.log:
                console.log(traceMessage);
                break;
            case trace.messageType.info:
                console.info(traceMessage);
                break;
            case trace.messageType.warn:
                console.warn(traceMessage);
                break;
            case trace.messageType.error:
                console.error(traceMessage);
                break;
        }
    };
    return StampedWriter;
}());
function setupTimestampConsoleWriter() {
    trace.clearWriters();
    trace.addWriter(new StampedWriter);
}
exports.setupTimestampConsoleWriter = setupTimestampConsoleWriter;

traceWriter.ts

import * as trace from "tns-core-modules/trace";

class StampedWriter implements trace.TraceWriter {
  private startTime: Date;
  private lastCalledAt: Date;

  write(message: any, category: string, type?: number) {
    if (!console) return;

    let newTime = new Date();
    if (!this.startTime || (newTime.getTime()- this.lastCalledAt.getTime())>3000) {
      this.startTime = newTime;
    }
    this.lastCalledAt = newTime;
    let timeDiff = newTime.getTime()- this.startTime.getTime();

    var msgType = type || trace.messageType.log;
    var traceMessage = "time +" + timeDiff+ " " + category + ": " + message;

    switch (msgType) {
      case trace.messageType.log:
        console.log(traceMessage);
        break;
      case trace.messageType.info:
        console.info(traceMessage);
        break;
      case trace.messageType.warn:
        console.warn(traceMessage);
        break;
      case trace.messageType.error:
        console.error(traceMessage);
        break;
    }
  }
}

export function setupTimestampConsoleWriter() {
  trace.clearWriters();
  trace.addWriter(new StampedWriter);
}