CSS Class from `class=""` Attribute

const re = new RegExp("class\\s*=\\s*[\"']([^\"']+)[\"']", "gi");
const input = "<div class=\"btn primary\">";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

import re

pattern = re.compile(r"class\\s*=\\s*[\"']([^\"']+)[\"']", re.IGNORECASE)
input_text = "<div class=\"btn primary\">"
for m in pattern.finditer(input_text):
    print(m.group(0))

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`(?i)class\s*=\s*["']([^"']+)["']`)
	input := `<div class="btn primary">`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}