Add formatting flag

Add formatting flag for output format.

Author: hachibu

README.md

@@ -1,6 +1,7 @@
 # Datelta (Date + Delta = Datelta)
 
-CLI tool to diff dates.
+CLI tool to diff dates with millisecond precision and support for multiple
+output formats (e.g. json, yaml).
 
 ## Quick Start
 
@@ -52,3 +53,4 @@ datelta --start "mar 2006" | jq
 | ------------------- | -------------------------------- |
 | deno task install   | Install datelta as an executable |
 | deno task uninstall | Uninstall datelta                |
+| deno task dev       | Start development mode           |

deno.lock

@@ -1,4 +1,4 @@
-import { toUTC, floorDivMod, floorMod } from "./util.ts";
+import { floorDivMod, floorMod, toUTC } from "./util.ts";
 
 export interface DateDiff {
   years: number;

src/lib.ts

@@ -1,22 +1,25 @@
 import { dateDiff } from "./lib.ts";
-import { parse } from "https://deno.land/std@0.202.0/flags/mod.ts";
+import { parseArgs } from "https://deno.land/std@0.217.0/cli/parse_args.ts";
+import * as YAML from "https://deno.land/std@0.217.0/yaml/mod.ts";
 
-const version = "v0.0.3";
-const help = `Usage: datelta ${version}
+const version = "v0.1.0";
+const help = `datelta ${version}
 
-Datelta calculates the difference between 2 dates.
+Datelta calculates the difference between 2 dates with millisecond precision.
 
 Options:
           --start     Start date (default: now).
           --end       End date (default: now).
+          --fmt       Output format (default: json, options: json, yaml).
       -h, --help      Print help.
       -V, --version   Print version.`;
 
 function main() {
-  const flags = parse(Deno.args, {
+  const flags = parseArgs(Deno.args, {
     boolean: ["help", "h", "version", "V"],
-    string: ["start", "end"],
+    string: ["start", "end", "fmt"],
   });
+  const allowedFmts = ["json", "yaml"];
 
   if (flags.help || flags.h) {
     return console.log(help);
@@ -32,12 +35,30 @@ function main() {
     endDate = new Date(flags.end);
   } else if (flags.start) {
     startDate = new Date(flags.start);
+  } else {
+    return console.log(help);
+  }
+
+  const fmt = flags.fmt ?? "json";
+  if (!allowedFmts.includes(fmt)) {
+    return console.error(
+      `invalid argument: fmt was "${fmt}" expected one of:`,
+      allowedFmts,
+    );
   }
 
-  const diff = dateDiff(startDate, endDate);
-  const diffJSON = JSON.stringify(diff);
+  const dd = { ...dateDiff(startDate, endDate) };
 
-  console.log(diffJSON);
+  if (fmt === "json") {
+    console.log(JSON.stringify(dd));
+  } else if (fmt === "yaml") {
+    console.log(YAML.stringify(dd));
+  } else {
+    return console.error(
+      `invalid argument: fmt was "${fmt}" expected one of:`,
+      allowedFmts,
+    );
+  }
 }
 
 if (import.meta.main) {

src/main.ts

@@ -6,13 +6,13 @@ export function toUTC(date: Date): number {
     date.getHours(),
     date.getMinutes(),
     date.getSeconds(),
-    date.getMilliseconds()
+    date.getMilliseconds(),
   );
 }
 
 export function floorDivMod(
   n: number,
-  m: number
+  m: number,
 ): [quotient: number, remainder: number] {
   const q = Math.floor(n / m);
   const r = n % m;