目標はこんな感じ

index.htmlを新規作成後、p5 と入力したら候補が出てきて、それを選択すると

いつも書く内容が一発ででてくるようにしたいです

vueはこんな感じにしてます

設定方法

Macであれば、Code > 基本設定 > ユーザースニペット

すでに自分はいろいろ作っちゃってますが…html.jsonを選んで

exampleがあるので、それに則ってvueやp5jsで最初必ず書くテンプレートを書いていきます
（ダブルクォートやらが面倒ですね、もっといいやり方あったら知りたいですが、一回っきりなので…）

自分の記述内容はこちら

{
	// Place your snippets for html here. Each snippet is defined under a snippet name and has a prefix, body and 
	// description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the 
	// same ids are connected.
	// Example:
	// "Print to console": {
	// 	"prefix": "log",
	// 	"body": [
	// 		"console.log('$1');",
	// 		"$2"
	// 	],
	// 	"description": "Log output to console"
	// }
	"vue": {
		"prefix": "vue-html",
		"body": [
			"<!DOCTYPE html>",
			"<html lang=\"en\">",
			"",
			"<head>",
			"  <meta charset=\"UTF-8\">",
			"  <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">",
			"  <title>Document</title>",
			"</head>",
			"",
			"<body>",
			"  <div id=\"app\">",
			"",
			"  </div>",
			"",
			"  <script src=\"https://unpkg.com/vue\"></script>",
			"  <script>",
			"    const app = new Vue({",
			"      el: '#app',",
			"      data: {",
			"      },",
			"      mounted: async function () {",
			"      }",
			"    })",
			"  </script>",
			"",
			"</body>",
			"",
			"</html>"
		],
		"description": "Quick start vue"
	},
	"p5": {
		"prefix": "p5-html",
		"body": [
			"<!DOCTYPE html>",
			"<html lang=\"en\">",
			"",
			"<head>",
			"  <meta charset=\"UTF-8\">",
			"  <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">",
			"  <title>p5</title>",
			"  <script src=\"https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.3.1/p5.js\"></script>",
			"  <script src=\"https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.3.1/addons/p5.sound.min.js\"></script>",
			"  <script src=\"sketch.js\"></script>",
			"  <style>",
			"    html, body {",
			"      margin: 0;",
			"      padding: 0;",
			"    }",
			"  </style>",
			"</head>",
			"",
			"<body>",
			"</body>",
			"",
			"</html>"
		],
		"description": "Quick start p5"
	}
}

p5jsもヴァージョン変わったら更新しなきゃなやつですね