maint/build ~ CJS+ESM packaging + deno support

- ref: [Node Modules at War](https://redfin.engineering/node-modules-at-war-why-commonjs-and-es-modules-cant-get-along-9617135eeca1) @@ <https://archive.is/zl0qg>
- ref: [yargs ~ 'Road to ESM/Deno'](yargs/yargs#1706)

## discussion

As suggested in "Node Modules at War", an ESM wrapper is used to provide basic ESM
support. However, `deno` is unable to use that ESM module, failing to load the
transitive CJS module with `'../index.js' does not provide an export named 'default'`.
So, `deno` is instead referred to a full ESM transpile.

As `deno` is it's own animal, there is no issue with CJS and ESM referring to differing
modules, either for installation or creating subtle code issues.

package.json

@@ -14,14 +14,24 @@
 	"files": [
 		"build/cjs",
 		"build/esm",
-		"build/umd",
 		"build/types",
 		"CHANGELOG.mkd",
 		"LICENSE",
 		"README.md"
 	],
 	"main": "build/cjs/index.js",
 	"types": "build/types/index.d.ts",
+	"exports": {
+		"./package.json": "./package.json",
+		".": [
+			{
+				"deno": "./src/mod.deno.ts",
+				"import": "./build/cjs/esm-wrapper/index.js",
+				"require": "./build/cjs/index.js"
+			},
+			"./build/cjs/index.js"
+		]
+	},
 	"keywords": [
 		"common",
 		"cross-platform",
@@ -43,6 +53,7 @@
 		"# build # build/compile package": "",
 		"build": "run-s _:build",
 		"build:cjs": "tsc -p tsconfig/tsconfig.cjs.json",
+		"build:cjs/esm": "shx mkdir -p build/cjs && shx cp -r src/esm-wrapper build/cjs",
 		"## build:esm # [2020-12-22; rivy] TS compiles to ESMs are broken due to extension mishandling (use `rollup`)": "tsc -p tsconfig/tsconfig.esm.json",
 		"build:esm": "rollup -c",
 		"build:umd": "tsc -p tsconfig/tsconfig.umd.json",
@@ -51,7 +62,7 @@
 		"# clean # remove build artifacts": "",
 		"clean": "rimraf build dist",
 		"# coverage # calcuate and display (or send) code coverage [alias: 'cov']": "",
-		"coverage": "run-s --silent _:max-node-8 && echo-cli \"[coverage] WARN Code coverage skipped [for NodeJS < v10]\" 1>&2 || run-s _:coverage",
+		"coverage": "run-s --silent _:max-node-8 && shx echo \"[coverage] WARN Code coverage skipped [for NodeJS < v10]\" 1>&2 || run-s _:coverage",
 		"cov": "run-s coverage",
 		"cov:html": "nyc report --reporter=html",
 		"cov:send": "nyc report --reporter=text-lcov | codecov --disable=gcov --pipe",
@@ -66,7 +77,7 @@
 		"# help # display help": "",
 		"help": "< package.json node -e \"s = {p:'',e:'npm'}; if (new String(process.env.npm_execpath).match(/yarn.js$/)) { s = {p:'\\n',e:'yarn'}; }; console.log('%susage: \\`%s run TARGET [TARGET..]\\`\\n\\nTARGETs:\\n', s.p, s.e); re = /^.*?\\x22(?:\\W+\\s*)([^#\\x22]+)\\s+#+\\s+([^#\\x22]+?)(\\s+#+)?\\x22.*$/; require('readline').createInterface({ input: process.stdin, output: process.stdout, terminal: false }).on('line', function(line){ if (match = re.exec(line)) { console.log('%s %s', match[1].padEnd(19), match[2]); } });\"",
 		"# lint # check for package code 'lint'": "",
-		"lint": "run-s --silent _:max-node-8 && echo-cli \"[lint] WARN Lint checks skipped [for NodeJS < v10]\" 1>&2 || run-p lint:*",
+		"lint": "run-s --silent _:max-node-8 && shx echo \"[lint] WARN Lint checks skipped [for NodeJS < v10]\" 1>&2 || run-p lint:*",
 		"# lint:lint # check for code 'lint' (using `eslint`)": "",
 		"lint:lint": "eslint .",
 		"# lint:spell # check for spelling errors (using `cspell`)": "",
@@ -86,19 +97,19 @@
 		"# test:types # check for type declaration errors (using `tsd`)": "",
 		"test:types": "tsd",
 		"# update:changelog # update CHANGELOG (using `git changelog ...`)": "",
-		"update:changelog": "run-s --silent _:update:changelog && echo-cli \"[update] info CHANGELOG updated\"",
+		"update:changelog": "run-s --silent _:update:changelog && shx echo \"[update] info CHANGELOG updated\"",
 		"_:build": "exec-if-updated --source package.json --source tsconfig.json --source \"tsconfig/**\" --source rollup.config.js --source \"src/**\" --target \"build/**\" run-p \"build:*\"",
 		"_:build+test:code": "exec-if-updated --source package.json --source tsconfig.json --source \"tsconfig/**\" --source rollup.config.js --source \"src/**\" --target \"build/**\" run-p \"build:*\" && run-s test:code",
 		"_:coverage": "run-s _:build+test:code && is-ci && run-s cov:send || run-s cov:view",
-		"_:exists:git-changelog": "node -e \"if (!require('command-exists').sync('git-changelog')){process.exit(1);};\" || (echo-cli \"WARN `git-changelog` missing (try `go get -u github.com/rivy-go/git-changelog/cmd/git-changelog`)\" & exit 1)",
+		"_:exists:git-changelog": "node -e \"if (!require('command-exists').sync('git-changelog')){process.exit(1);};\" || (shx echo \"WARN `git-changelog` missing (try `go get -u github.com/rivy-go/git-changelog/cmd/git-changelog`)\" & exit 1)",
 		"_:max-node-8": "is-node-not-modern 10",
 		"_:min-node-10": "is-node-modern 10",
 		"_:vcs-clean": "git diff --quiet",
-		"_:vcs-clean-err": "run-s --silent _:vcs-clean || (echo-cli \"[vcs] ERR! Uncommitted changes\" 1>&2 & exit 1)",
+		"_:vcs-clean-err": "run-s --silent _:vcs-clean || (shx echo \"[vcs] ERR! Uncommitted changes\" 1>&2 & exit 1)",
 		"_:vcs-strictly-clean": "git status --porcelain | node -e \"process.stdin.on('data',function(_){process.exit(1);});\"",
-		"_:vcs-strictly-clean-err": "run-s --silent _:vcs-strictly-clean || (echo-cli \"[vcs] ERR! Uncommitted changes and/or untracked files\" 1>&2 & exit 1)",
-		"_:update:changelog": "run-s --silent _:exists:git-changelog && git changelog > CHANGELOG.mkd || echo-cli \"[update] info CHANGELOG not updated\" 1>&2",
-		"_:version:update:changelog": "run-s --silent _:exists:git-changelog && node -e \"v=require('./package.json').version; result=require('child_process').spawnSync('git changelog --next-tag v'+v,{shell:true,encoding:'utf-8'}); if (result.status != 0) {console.error('ERR! '+result.stderr); process.exit(1);} else {require('fs').writeFileSync('CHANGELOG.mkd',result.stdout);};\" || echo-cli \"[version] WARN CHANGELOG not updated\" 1>&2",
+		"_:vcs-strictly-clean-err": "run-s --silent _:vcs-strictly-clean || (shx echo \"[vcs] ERR! Uncommitted changes and/or untracked files\" 1>&2 & exit 1)",
+		"_:update:changelog": "run-s --silent _:exists:git-changelog && git changelog > CHANGELOG.mkd || shx echo \"[update] info CHANGELOG not updated\" 1>&2",
+		"_:version:update:changelog": "run-s --silent _:exists:git-changelog && node -e \"v=require('./package.json').version; result=require('child_process').spawnSync('git changelog --next-tag v'+v,{shell:true,encoding:'utf-8'}); if (result.status != 0) {console.error('ERR! '+result.stderr); process.exit(1);} else {require('fs').writeFileSync('CHANGELOG.mkd',result.stdout);};\" || shx echo \"[version] WARN CHANGELOG not updated\" 1>&2",
 		"prepublishOnly": "run-s update:* test _:vcs-strictly-clean-err",
 		"preversion": "run-s test",
 		"version": "run-s _:version:update:changelog lint:spell && git add CHANGELOG.mkd"
@@ -118,7 +129,6 @@
 		"coveralls": "^3.0.5",
 		"cross-spawn": "^6.0.5",
 		"cspell": "^4.1.2",
-		"echo-cli": "^1.0.8",
 		"eslint": "^7.11.0",
 		"eslint-config-prettier": "^6.11.0",
 		"eslint-plugin-eslint-comments": "^3.2.0",
@@ -134,6 +144,7 @@
 		"rimraf": "^3.0.2",
 		"rollup": "^2.35.1",
 		"rollup-plugin-typescript2": "^0.29.0",
+		"shx": "^0.3.3",
 		"ts-node": "^9.0.0",
 		"tsd": "^0.13.1",
 		"typescript": "^4.1.3"

src/esm-wrapper/index.js

@@ -0,0 +1,10 @@
+// # spell-checker:ignore Deno
+import _ from '../index.js';
+// note: not usable by `deno`;
+//   ...`deno` is unable to (the CJS module) '../index.js' via import => `'../index.js' does not provide an export named 'default'`
+
+// export const OSPathsWithAdaption = _['_esm!'].OSPathsWithAdaption;
+// const default_ = _['_esm!'].default;
+// export default default_;
+const default_ = _;
+export default default_;

src/esm-wrapper/package.json

@@ -0,0 +1 @@
+{"type": "module"}

src/index.ts

@@ -2,7 +2,7 @@
 import { default as OSPathsWithAdaption } from './lib/OSPaths';
 import adapter from './platform-shims/node';
 
-export * from './lib/OSPaths';
+// export * from './lib/OSPaths';
 
 const default_ = OSPathsWithAdaption(adapter);
 export default default_;