func Html2str(html string) string {
	src := string(html)
	re, _ := regexp.Compile("\\<[\\S\\s]+?\\>")
	src = re.ReplaceAllStringFunc(src, strings.ToLower)
	re, _ = regexp.Compile("\\<style[\\S\\s]+?\\</style\\>")
	src = re.ReplaceAllString(src, "")
	re, _ = regexp.Compile("\\<script[\\S\\s]+?\\</script\\>")
	src = re.ReplaceAllString(src, "")
	re, _ = regexp.Compile("\\<[\\S\\s]+?\\>")
	src = re.ReplaceAllString(src, "\n")
	re, _ = regexp.Compile("\\s{2,}")
	src = re.ReplaceAllString(src, "\n")
	return strings.TrimSpace(src)
}
Html2str returns escaping text convert from html.
package beego
import (
	"errors"
	"fmt"
	"html/template"
	"net/url"
	"reflect"
	"regexp"
	"strconv"
	"strings"
	"time"
)
func Substr(s string, start, length int) string {
	bt := []rune(s)
	if start < 0 {
		start = 0
	}
	if start > len(bt) {
		start = start % len(bt)
	}
	var end int
	if (start + length) > (len(bt) - 1) {
		end = len(bt)
	} else {
		end = start + length
	}
	return string(bt[start:end])
}