Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Html.php
public function canRead($pFilename)
    {
        // Check if file exists
        try {
            $this->openFile($pFilename);
        } catch (Exception $e) {
            return false;
        }

        $beginning = $this->readBeginning();
        $startWithTag = self::startsWithTag($beginning);
        $containsTags = self::containsTags($beginning);
        $endsWithTag = self::endsWithTag($this->readEnding());

        fclose($this->fileHandle);

        return $startWithTag && $containsTags && $endsWithTag;
    }
public function canRead($pFilename)
    {
        // Check if file exists
        try {
            $this->openFile($pFilename);
        } catch (Exception $e) {
            return false;
        }

        $beginning = $this->readBeginning();
        $startWithTag = self::startsWithTag($beginning);
        $containsTags = self::containsTags($beginning);
        $endsWithTag = self::endsWithTag($this->readEnding());

        fclose($this->fileHandle);

        return $startWithTag && $containsTags && $endsWithTag;
    }
Validate that the current file is an HTML file.

@param string $pFilename

@return bool