我正在准备一个网站的面试问题，并且无法想到关注的解决方案，有些人能帮忙吗？
编写一个函数以从给定的Url中检索第一个H1元素的值。
包含属性的H1 H1包含嵌套标签 在HTML中找不到H1
答案 0 :(得分：0)
查看Html敏捷包http://htmlagilitypack.codeplex.com/。然后，您可以使用linq来回答问题。
答案 1 :(得分：0)
所以我在网上查了一下，然后找到了一个脚本并对其进行了修改。 我从GitHub上的一个项目中获取了file_get_contents函数。
我希望它会起作用，告诉我，如果不是，我会尝试解决它。
get.js（var H1是第一个标题）：
function file_get_contents(url, flags, context, offset, maxLen) {
// discuss at: http://phpjs.org/functions/file_get_contents/
// original by: Legaev Andrey
// input by: Jani Hartikainen
// input by: Raphael (Ao) RUDLER
// improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// improved by: Brett Zamir (http://brett-zamir.me)
// bugfixed by: Brett Zamir (http://brett-zamir.me)
// note: This function uses XmlHttpRequest and cannot retrieve resource from different domain without modifications.
// note: Synchronous by default (as in PHP) so may lock up browser. Can
// note: get async by setting a custom "phpjs.async" property to true and "notification" for an
// note: optional callback (both as context params, with responseText, and other JS-specific
// note: request properties available via 'this'). Note that file_get_contents() will not return the text
// note: in such a case (use this.responseText within the callback). Or, consider using
// note: jQuery's: $('#divId').load('http://url') instead.
// note: The context argument is only implemented for http, and only partially (see below for
// note: "Presently unimplemented HTTP context options"); also the arguments passed to
// note: notification are incomplete
// test: skip
// example 1: var buf file_get_contents('http://google.com');
// example 1: buf.indexOf('Google') !== -1
// returns 1: true
var tmp, headers = [],
newTmp = [],
k = 0,
i = 0,
href = '',
pathPos = -1,
flagNames = 0,
content = null,
http_stream = false;
var func = function(value) {
return value.substring(1) !== '';
};
// BEGIN REDUNDANT
this.php_js = this.php_js || {};
this.php_js.ini = this.php_js.ini || {};
// END REDUNDANT
var ini = this.php_js.ini;
context = context || this.php_js.default_streams_context || null;
if (!flags) {
flags = 0;
}
var OPTS = {
FILE_USE_INCLUDE_PATH: 1,
FILE_TEXT: 32,
FILE_BINARY: 64
};
if (typeof flags === 'number') { // Allow for a single string or an array of string flags
flagNames = flags;
} else {
flags = [].concat(flags);
for (i = 0; i < flags.length; i++) {
if (OPTS[flags[i]]) {
flagNames = flagNames | OPTS[flags[i]];
}
}
}
if (flagNames & OPTS.FILE_BINARY && (flagNames & OPTS.FILE_TEXT)) { // These flags shouldn't be together
throw 'You cannot pass both FILE_BINARY and FILE_TEXT to file_get_contents()';
}
if ((flagNames & OPTS.FILE_USE_INCLUDE_PATH) && ini.include_path && ini.include_path.local_value) {
var slash = ini.include_path.local_value.indexOf('/') !== -1 ? '/' : '\\';
url = ini.include_path.local_value + slash + url;
} else if (!/^(https?|file):/.test(url)) { // Allow references within or below the same directory (should fix to allow other relative references or root reference; could make dependent on parse_url())
href = this.window.location.href;
pathPos = url.indexOf('/') === 0 ? href.indexOf('/', 8) - 1 : href.lastIndexOf('/');
url = href.slice(0, pathPos + 1) + url;
}
var http_options;
if (context) {
http_options = context.stream_options && context.stream_options.http;
http_stream = !! http_options;
}
if (!context || http_stream) {
var req = this.window.ActiveXObject ? new ActiveXObject('Microsoft.XMLHTTP') : new XMLHttpRequest();
if (!req) {
throw new Error('XMLHttpRequest not supported');
}
var method = http_stream ? http_options.method : 'GET';
var async = !! (context && context.stream_params && context.stream_params['phpjs.async']);
if (ini['phpjs.ajaxBypassCache'] && ini['phpjs.ajaxBypassCache'].local_value) {
url += (url.match(/\?/) == null ? '?' : '&') + (new Date())
.getTime(); // Give optional means of forcing bypass of cache
}
req.open(method, url, async);
if (async) {
var notification = context.stream_params.notification;
if (typeof notification === 'function') {
// Fix: make work with req.addEventListener if available: https://developer.mozilla.org/En/Using_XMLHttpRequest
if (0 && req.addEventListener) { // Unimplemented so don't allow to get here
/*
req.addEventListener('progress', updateProgress, false);
req.addEventListener('load', transferComplete, false);
req.addEventListener('error', transferFailed, false);
req.addEventListener('abort', transferCanceled, false);
*/
} else {
req.onreadystatechange = function(aEvt) { // aEvt has stopPropagation(), preventDefault(); see https://developer.mozilla.org/en/NsIDOMEvent
// Other XMLHttpRequest properties: multipart, responseXML, status, statusText, upload, withCredentials
/*
PHP Constants:
STREAM_NOTIFY_RESOLVE 1 A remote address required for this stream has been resolved, or the resolution failed. See severity for an indication of which happened.
STREAM_NOTIFY_CONNECT 2 A connection with an external resource has been established.
STREAM_NOTIFY_AUTH_REQUIRED 3 Additional authorization is required to access the specified resource. Typical issued with severity level of STREAM_NOTIFY_SEVERITY_ERR.
STREAM_NOTIFY_MIME_TYPE_IS 4 The mime-type of resource has been identified, refer to message for a description of the discovered type.
STREAM_NOTIFY_FILE_SIZE_IS 5 The size of the resource has been discovered.
STREAM_NOTIFY_REDIRECTED 6 The external resource has redirected the stream to an alternate location. Refer to message .
STREAM_NOTIFY_PROGRESS 7 Indicates current progress of the stream transfer in bytes_transferred and possibly bytes_max as well.
STREAM_NOTIFY_COMPLETED 8 There is no more data available on the stream.
STREAM_NOTIFY_FAILURE 9 A generic error occurred on the stream, consult message and message_code for details.
STREAM_NOTIFY_AUTH_RESULT 10 Authorization has been completed (with or without success).
STREAM_NOTIFY_SEVERITY_INFO 0 Normal, non-error related, notification.
STREAM_NOTIFY_SEVERITY_WARN 1 Non critical error condition. Processing may continue.
STREAM_NOTIFY_SEVERITY_ERR 2 A critical error occurred. Processing cannot continue.
*/
var objContext = {
responseText: req.responseText,
responseXML: req.responseXML,
status: req.status,
statusText: req.statusText,
readyState: req.readyState,
evt: aEvt
}; // properties are not available in PHP, but offered on notification via 'this' for convenience
// notification args: notification_code, severity, message, message_code, bytes_transferred, bytes_max (all int's except string 'message')
// Need to add message, etc.
var bytes_transferred;
switch (req.readyState) {
case 0:
// UNINITIALIZED open() has not been called yet.
notification.call(objContext, 0, 0, '', 0, 0, 0);
break;
case 1:
// LOADING send() has not been called yet.
notification.call(objContext, 0, 0, '', 0, 0, 0);
break;
case 2:
// LOADED send() has been called, and headers and status are available.
notification.call(objContext, 0, 0, '', 0, 0, 0);
break;
case 3:
// INTERACTIVE Downloading; responseText holds partial data.
bytes_transferred = req.responseText.length * 2; // One character is two bytes
notification.call(objContext, 7, 0, '', 0, bytes_transferred, 0);
break;
case 4:
// COMPLETED The operation is complete.
if (req.status >= 200 && req.status < 400) {
bytes_transferred = req.responseText.length * 2; // One character is two bytes
notification.call(objContext, 8, 0, '', req.status, bytes_transferred, 0);
} else if (req.status === 403) { // Fix: These two are finished except for message
notification.call(objContext, 10, 2, '', req.status, 0, 0);
} else { // Errors
notification.call(objContext, 9, 2, '', req.status, 0, 0);
}
break;
default:
throw 'Unrecognized ready state for file_get_contents()';
}
};
}
}
}
if (http_stream) {
var sendHeaders = http_options.header && http_options.header.split(/\r?\n/);
var userAgentSent = false;
for (i = 0; i < sendHeaders.length; i++) {
var sendHeader = sendHeaders[i];
var breakPos = sendHeader.search(/:\s*/);
var sendHeaderName = sendHeader.substring(0, breakPos);
req.setRequestHeader(sendHeaderName, sendHeader.substring(breakPos + 1));
if (sendHeaderName === 'User-Agent') {
userAgentSent = true;
}
}
if (!userAgentSent) {
var user_agent = http_options.user_agent || (ini.user_agent && ini.user_agent.local_value);
if (user_agent) {
req.setRequestHeader('User-Agent', user_agent);
}
}
content = http_options.content || null;
/*
// Presently unimplemented HTTP context options
var request_fulluri = http_options.request_fulluri || false; // When set to TRUE, the entire URI will be used when constructing the request. (i.e. GET http://www.example.com/path/to/file.html HTTP/1.0). While this is a non-standard request format, some proxy servers require it.
var max_redirects = http_options.max_redirects || 20; // The max number of redirects to follow. Value 1 or less means that no redirects are followed.
var protocol_version = http_options.protocol_version || 1.0; // HTTP protocol version
var timeout = http_options.timeout || (ini.default_socket_timeout && ini.default_socket_timeout.local_value); // Read timeout in seconds, specified by a float
var ignore_errors = http_options.ignore_errors || false; // Fetch the content even on failure status codes.
*/
}
if (flagNames & OPTS.FILE_TEXT) { // Overrides how encoding is treated (regardless of what is returned from the server)
var content_type = 'text/html';
if (http_options && http_options['phpjs.override']) { // Fix: Could allow for non-HTTP as well
content_type = http_options['phpjs.override']; // We use this, e.g., in gettext-related functions if character set
// overridden earlier by bind_textdomain_codeset()
} else {
var encoding = (ini['unicode.stream_encoding'] && ini['unicode.stream_encoding'].local_value) ||
'UTF-8';
if (http_options && http_options.header && (/^content-type:/im)
.test(http_options.header)) { // We'll assume a content-type expects its own specified encoding if present
content_type = http_options.header.match(/^content-type:\s*(.*)$/im)[1]; // We let any header encoding stand
}
if (!(/;\s*charset=/)
.test(content_type)) { // If no encoding
content_type += '; charset=' + encoding;
}
}
req.overrideMimeType(content_type);
}
// Default is FILE_BINARY, but for binary, we apparently deviate from PHP in requiring the flag, since many if not
// most people will also want a way to have it be auto-converted into native JavaScript text instead
else if (flagNames & OPTS.FILE_BINARY) { // Trick at https://developer.mozilla.org/En/Using_XMLHttpRequest to get binary
req.overrideMimeType('text/plain; charset=x-user-defined');
// Getting an individual byte then requires:
// responseText.charCodeAt(x) & 0xFF; // throw away high-order byte (f7) where x is 0 to responseText.length-1 (see notes in our substr())
}
try {
if (http_options && http_options['phpjs.sendAsBinary']) { // For content sent in a POST or PUT request (use with file_put_contents()?)
req.sendAsBinary(content); // In Firefox, only available FF3+
} else {
req.send(content);
}
} catch (e) {
// catches exception reported in issue #66
return false;
}
tmp = req.getAllResponseHeaders();
if (tmp) {
tmp = tmp.split('\n');
for (k = 0; k < tmp.length; k++) {
if (func(tmp[k])) {
newTmp.push(tmp[k]);
}
}
tmp = newTmp;
for (i = 0; i < tmp.length; i++) {
headers[i] = tmp[i];
}
this.$http_response_header = headers; // see http://php.net/manual/en/reserved.variables.httpresponseheader.php
}
if (offset || maxLen) {
if (maxLen) {
return req.responseText.substr(offset || 0, maxLen);
}
return req.responseText.substr(offset);
}
return req.responseText;
}
return false;
}
var filecontent = file_get_contents("www.example.com");
var H1 = $( "h1" ).first().val();
答案 2 :(得分：0)
如果您使用jquery在客户端进行，您可以像这样做
$('#mydiv').load("http://localhost/mypage.html");
var firstH1 = $('#mydiv').children('h1:first-child');
console.log(firstH1);