ter = array_value($config, 'filter'); $arr = array_value($filter, $type); $enable = array_value($arr, 'enable'); $wordarr = array_value($arr, 'keyword'); if (0 == $enable || empty($wordarr)) return FALSE; foreach ($wordarr as $_keyword) { if (!$_keyword) continue; $r = strpos(strtolower($keyword), strtolower($_keyword)); if (FALSE !== $r) { $error = $_keyword; return TRUE; } } return FALSE; } // return http://domain.com OR https://domain.com function url_prefix() { $http = ((isset($_SERVER['HTTPS']) && 'on' == $_SERVER['HTTPS']) || (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')) ? 'https://' : 'http://'; return $http . $_SERVER['HTTP_HOST']; } // 唯一身份ID function uniq_id() { return uniqid(substr(md5(microtime(true) . mt_rand(1000, 9999)), 8, 8)); } // 生成订单号 14位 function trade_no() { $trade_no = str_replace('.', '', microtime(1)); $strlen = mb_strlen($trade_no, 'UTF-8'); $strlen = 14 - $strlen; $str = ''; if ($strlen) { for ($i = 0; $i <= $strlen; $i++) { if ($i < $strlen) $str .= '0'; } } return $trade_no . $str; } // 生成订单号 16位 function trade_no_16() { $explode = explode(' ', microtime()); $trade_no = $explode[1] . mb_substr($explode[0], 2, 6, 'UTF-8'); return $trade_no; } // 当前年的天数 function date_year($time = NULL) { $time = intval($time) ? $time : time(); return date('L', $time) + 365; } // 当前年份中的第几天 function date_z($time = NULL) { $time = intval($time) ? $time : time(); return date('z', $time); } // 当前月份中的第几天，没有前导零 1 到 31 function date_j($time = NULL) { $time = intval($time) ? $time : time(); return date('j', $time); } // 当前月份中的第几天，有前导零的2位数字 01 到 31 function date_d($time = NULL) { $time = intval($time) ? $time : time(); return date('d', $time); } // 当前时间为星期中的第几天 数字表示 1表示星期一 到 7表示星期天 function date_w_n($time = NULL) { $time = intval($time) ? $time : time(); return date('N', $time); } // 当前日第几周 function date_d_w($time = NULL) { $time = intval($time) ? $time : time(); return date('W', $time); } // 当前几月 没有前导零1-12 function date_n($time = NULL) { $time = intval($time) ? $time : time(); return date('n', $time); } // 当前月的天数 function date_t($time = NULL) { $time = intval($time) ? $time : time(); return date('t', $time); } // 0 o'clock on the day function clock_zero() { return strtotime(date('Ymd')); } // 24 o'clock on the day function clock_twenty_four() { return strtotime(date('Ymd')) + 86400; } // 8点过期 / expired at 8 a.m. function eight_expired($time = NULL) { $time = intval($time) ? $time : time(); // 当前时间大于8点则改为第二天8点过期 $life = date('G') <= 8 ? (strtotime(date('Ymd')) + 28800 - $time) : clock_twenty_four() - $time + 28800; return $life; } // 24点过期 / expired at 24 a.m. function twenty_four_expired($time = NULL) { $time = intval($time) ? $time : time(); $twenty_four = clock_twenty_four(); $life = $twenty_four - $time; return $life; } /** * @param $url 提交地址 * @param string $post POST数组 / 空为GET获取数据 / $post='GET'获取连续跳转最终URL * @param string $cookie cookie * @param int $timeout 超时 * @param int $ms 设为1是毫秒 * @return mixed 返回数据 */ function https_request($url, $post = '', $cookie = '', $timeout = 30, $ms = 0) { if (empty($url)) return FALSE; if (version_compare(PHP_VERSION, '5.2.3', '<')) { $ms = 0; $timeout = 30; } is_array($post) and $post = http_build_query($post); // 没有安装curl 使用http的形式，支持post if (!extension_loaded('curl')) { //throw new Exception('server not install CURL'); if ($post) { return https_post($url, $post, $cookie, $timeout); } else { return http_get($url, $cookie, $timeout); } } is_array($cookie) and $cookie = http_build_query($cookie); $curl = curl_init(); // 返回执行结果，不输出 curl_setopt($curl, CURLOPT_RETURNTRANSFER, true); //php5.5跟php5.6中的CURLOPT_SAFE_UPLOAD的默认值不同 if (class_exists('\CURLFile')) { curl_setopt($curl, CURLOPT_SAFE_UPLOAD, true); } else { defined('CURLOPT_SAFE_UPLOAD') and curl_setopt($curl, CURLOPT_SAFE_UPLOAD, false); } // 设定请求的RUL curl_setopt($curl, CURLOPT_URL, $url); // 设定返回信息中包含响应信息头 if (ini_get('safe_mode') && ini_get('open_basedir')) { // $post参数必须为GET if ('GET' == $post) { // 安全模式时将头文件的信息作为数据流输出 curl_setopt($curl, CURLOPT_HEADER, true); // 安全模式采用连续抓取 curl_setopt($curl, CURLOPT_NOBODY, true); } } else { curl_setopt($curl, CURLOPT_HEADER, false); // 允许跳转10次 curl_setopt($curl, CURLOPT_MAXREDIRS, 10); // 使用自动跳转，返回最后的Location curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true); } $ua1 = 'Mozilla/5.0 (iPhone; CPU iPhone OS 13_2_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/13.0.3 Mobile/15E148 Safari/604.1'; $ua = empty($_SERVER["HTTP_USER_AGENT"]) ? $ua1 : $_SERVER["HTTP_USER_AGENT"]; curl_setopt($curl, CURLOPT_USERAGENT, $ua); // 兼容HTTPS if (FALSE !== stripos($url, 'https://')) { curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE); curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE); //ssl版本控制 //curl_setopt($curl, CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1); curl_setopt($curl, CURLOPT_SSLVERSION, true); } $header = array('Content-type: application/x-www-form-urlencoded;charset=UTF-8', 'X-Requested-With: XMLHttpRequest'); $cookie and $header[] = "Cookie: $cookie"; curl_setopt($curl, CURLOPT_HTTPHEADER, $header); if ($post) { // POST curl_setopt($curl, CURLOPT_POST, true); // 自动设置Referer curl_setopt($curl, CURLOPT_AUTOREFERER, true); curl_setopt($curl, CURLOPT_POSTFIELDS, $post); } if ($ms) { curl_setopt($curl, CURLOPT_NOSIGNAL, true); // 设置毫秒超时 curl_setopt($curl, CURLOPT_TIMEOUT_MS, intval($timeout)); // 超时毫秒 } else { curl_setopt($curl, CURLOPT_TIMEOUT, intval($timeout)); // 秒超时 } //优先解析 IPv6 超时后IPv4 //curl_setopt($curl, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4); curl_setopt($curl, CURLOPT_ENCODING, 'gzip'); // 返回执行结果 $output = curl_exec($curl); // 有效URL，输出URL非URL页面内容 CURLOPT_RETURNTRANSFER 必须为false 'GET' == $post and $output = curl_getinfo($curl, CURLINFO_EFFECTIVE_URL); curl_close($curl); return $output; } function save_image($img) { $ch = curl_init(); // 设定请求的RUL curl_setopt($ch, CURLOPT_URL, $img); // 设定返回信息中包含响应信息头 启用时会将头文件的信息作为数据流输出 //curl_setopt($ch, CURLOPT_HEADER, false); //curl_setopt($ch, CURLOPT_USERAGENT, $_SERVER["HTTP_USER_AGENT"]); // true表示$html,false表示echo $html curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10); curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); //curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1); //curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 0); curl_setopt($ch, CURLOPT_ENCODING, 'gzip'); $output = curl_exec($ch); curl_close($ch); return $output; } // 计算字串宽度:剧中对齐(字体大小/字串内容/字体链接/背景宽度/倍数) function calculate_str_width($size, $str, $font, $width, $multiple = 2) { $box = imagettfbbox($size, 0, $font, $str); return ($width - $box[4] - $box[6]) / $multiple; } // 搜索目录下的文件 比对文件后缀 function search_directory($path) { if (is_dir($path)) { $paths = scandir($path); foreach ($paths as $val) { $sub_path = $path . '/' . $val; if ('.' == $val || '..' == $val) { continue; } else if (is_dir($sub_path)) { //echo '目录名:' . $val . '
'; search_directory($sub_path); } else { //echo ' 最底层文件: ' . $path . '/' . $val . '
'; $ext = strtolower(file_ext($sub_path)); if (in_array($ext, array('php', 'asp', 'jsp', 'cgi', 'exe', 'dll'), TRUE)) { echo '异常文件：' . $sub_path . '
'; } } } } } // 一维数组转字符串 $sign待签名字符串 $url为urlencode转码GET参数字符串 function array_to_string($arr, &$sign = '', &$url = '') { if (count($arr) != count($arr, 1)) throw new Exception('Does not support multi-dimensional array to string'); // 注销签名 unset($arr['sign']); // 排序 ksort($arr); reset($arr); // 转字符串做签名 $url = ''; $sign = ''; foreach ($arr as $key => $val) { if (empty($val) || is_array($val)) continue; $url .= $key . '=' . urlencode($val) . '&'; $sign .= $key . '=' . $val . '&'; } $url = substr($url, 0, -1); $url = htmlspecialchars($url); $sign = substr($sign, 0, -1); } // 私钥生成签名 function rsa_create_sign($data, $key, $sign_type = 'RSA') { if (!function_exists('openssl_sign')) throw new Exception('OpenSSL extension is not enabled'); if (!defined('OPENSSL_ALGO_SHA256')) throw new Exception('Only versions above PHP 5.4.8 support SHA256'); $key = wordwrap($key, 64, "\n", true); if (FALSE === $key) throw new Exception('Private Key Error'); $key = "-----BEGIN RSA PRIVATE KEY-----\n$key\n-----END RSA PRIVATE KEY-----"; if ('RSA2' == $sign_type) { openssl_sign($data, $sign, $key, OPENSSL_ALGO_SHA256); } else { openssl_sign($data, $sign, $key, OPENSSL_ALGO_SHA1); } // 加密 return base64_encode($sign); } // 公钥验证签名 function rsa_verify_sign($data, $sign, $key, $sign_type = 'RSA') { $key = wordwrap($key, 64, "\n", true); if (FALSE === $key) throw new Exception('Public Key Error'); $key = "-----BEGIN PUBLIC KEY-----\n$key\n-----END PUBLIC KEY-----"; // 签名正确返回1 签名不正确返回0 错误-1 if ('RSA2' == $sign_type) { $result = openssl_verify($data, base64_decode($sign), $key, OPENSSL_ALGO_SHA256); } else { $result = openssl_verify($data, base64_decode($sign), $key, OPENSSL_ALGO_SHA1); } return $result === 1; } // Array to xml array('appid' => 'appid', 'code' => 'success') function array_to_xml($arr) { if (!is_array($arr) || empty($arr)) throw new Exception('Array Error'); $xml = ""; foreach ($arr as $key => $val) { if (is_numeric($val)) { $xml .= "<" . $key . ">" . $val . ""; } else { $xml .= "<" . $key . ">"; } } $xml .= ""; return $xml; } // Xml to array function xml_to_array($xml) { if (!$xml) throw new Exception('XML error'); $old = libxml_disable_entity_loader(true); // xml解析 $result = (array)simplexml_load_string($xml, null, LIBXML_NOCDATA | LIBXML_COMPACT); // 恢复旧值 if (FALSE === $old) libxml_disable_entity_loader(false); return $result; } // 逐行读取 function well_import($file) { if ($handle = fopen($file, 'r')) { while (!feof($handle)) { yield trim(fgets($handle)); } fclose($handle); } } // 计算总行数 function well_import_total($file, $key = 'well_import_total') { static $cache = array(); if (isset($cache[$key])) return $cache[$key]; $count = cache_get($key); if (NULL === $count) { $count = 0; $globs = well_import($file); while ($globs->valid()) { ++$count; $globs->next(); // 指向下一个 } $count and cache_set($key, $count, 300); } return $cache[$key] = $count; } $g_dir_file = FALSE; function well_search_dir($path) { global $g_dir_file; FALSE === $g_dir_file and $g_dir_file = array(); if (is_dir($path)) { $paths = scandir($path); foreach ($paths as $val) { $sub_path = $path . '/' . $val; if ('.' == $val || '..' == $val) { continue; } else if (is_dir($sub_path)) { well_search_dir($sub_path); } else { $g_dir_file[] = $sub_path; } } } return $g_dir_file; } ?>javascript - Event Listener Remove or Keep - Best Practice - Stack Overflow

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    I have quite a few jquery / javascript listeners on my web page and I will reduce them as much as I can. However, for the listeners that remain, there are scenarios where I make them display:none at certain points. Here are my questions:

    1) What is best practice regarding listeners, should I add or remove listeners as I show / hide elements?

    2) Which is best performance wise?

    3) If I end up having lots of listeners, is it best to apply an on listener event to the whole body, or is it best to apply listeners to only things that need listening to?

    I have quite a few jquery / javascript listeners on my web page and I will reduce them as much as I can. However, for the listeners that remain, there are scenarios where I make them display:none at certain points. Here are my questions:

    1) What is best practice regarding listeners, should I add or remove listeners as I show / hide elements?

    2) Which is best performance wise?

    3) If I end up having lots of listeners, is it best to apply an on listener event to the whole body, or is it best to apply listeners to only things that need listening to?

    • javascript
    • jquery
    • listener
    Share Improve this question edited Apr 17, 2015 at 20:15 Wickey312 asked Apr 17, 2015 at 20:10 Wickey312Wickey312 5766 silver badges16 bronze badges 1
    • 1 If you're going to show it later, hiding would usually be better than removing it all together – adeneo Commented Apr 17, 2015 at 20:11
    Add a ment  | 

    2 Answers 2

    Reset to default 8

    A general rule of thumb is as follows:

    Remove events on teardown.

    Since you are not removing the DOM element, the listener should persist, performance wise there is no drawback unless you have hundreds of thousands of listeners.

    The time it takes to micromanage hidden elements listeners aren't enough to outweigh any perceived performance gains.

    1. Remove listeners when you remove elements (teardown).
    2. Listen to a generic class applied to multiple elements instead of individual elements, use data attributes to identify them if required.
    3. Listen to things that need to be listened to.

    You can also use event delegation (bubbling) for when you have a large number of children that require listening to by listening on the parent:

    $('div').on('click', function (e) {
  // check e.target for specific child node you require listening on
})

    1/2) What is best practice regarding listeners, should I add or remove listeners as I show / hide elements? --> Adding/removing events is slow. You can probably benchmark it but the best remendation is to keep them and let the garbage collection handle it in case you delete objects. It saves you code and is probably more readable, plus garbage collection (cleanup) should ideally happen (depending on implementation and a host of other things) when the user is not waiting/interacting.

    2) Which is best performance wise? --> See 1. Benchmark it if you're unsure.

    3) If I end up having lots of listeners, is it best to apply an on listener event to the whole body, or is it best to apply listeners to only things that need listening to? --> How much. Is your code readable either way? If you end up listening to the entire body, your code will be handling a LOT more events (mouse over every single object, clicks, keyboard inputs etc.) and typically you'll want to then filter out only relevant events and dispatch them to the function. This makes your code very messy (lots of if/then) and will eventually end up costing you way more in performance than what you thought to save. The best thing is to only handle events on the objects that are relevant to your process. Way simpler, way easier, way faster.

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