I need to make a function in JavaScript to locate href inside the url that is given, and to return it as a string.
For example: http://stackoverflow.com/
So the function starts with: function example(url) {}
I want to find the first link inside this url that contain the words google.
In this page there is somewhere link like <a href:"http://google.com/asdasdadsa/asdada">
The function is to return the whole link as string.
So basically from what I can gather, you want to look at each link on the page and get the whole URL if it includes some string (i.e. google).
Here's a function that finds the first link matching a certain string:
function checkLinks( searchString ) {
var url;
// Go through each link
$('a').each( function ( ) {
// Check if the search string exists
if( $(this).attr('href').indexOf(searchString) != -1 ) {
url = $(this).attr('href');
// If we've found one, stop the each.
return false;
}
});
return url;
}
I've put together a jsfiddle showing an example of how this function could be used:
http://jsfiddle.net/K9KvS/1/
EDIT:
I've just seen you need to do this on a remote URL. You probably need to use AJAX to load in the code, then run this on the code you have. Unfortunately due to the same origin policy, you can't get this directly, so you'll need to run a server-side script on your server (e.g. using PHP) to load the content of the external page, then an AJAX call from your JS to pull it into your javascript.
Modified version to include an AJAX load of some code, then a find on that code:
// Create a function to do the actual search
function checkLinks( code, searchString ) {
var url;
// Search the code for all <a> tags, the loop over them
$(code).find('a').each( function ( ) {
// Check if there is a match (indexOf returns -1 if not)
if( $(this).attr('href').indexOf(searchString) != -1 ) {
// set the "url" variable to the href
url = $(this).attr('href');
// Stop looping
return false;
}
});
return url;
}
// Now, when the page loads, attach an AJAX call to a button with ID "linkchecker"
$( function ( ) {
$('#linkchecker').click( function( ) {
var code;
// Perform the AJAX call, load the data and call our function above to find "google.com"
$.get( 'load_code.php?url=http://www.google.com', function( data ) {
code = data;
alert( checkLinks( code, 'google.com' ) );
});
});
});
load_code.php would probably look something like this (probably with some error checking, etc):
<?php
$htm = file_get_contents($_GET['url']);
echo $htm;
?>
Update: Using Raw Javascript
We'll modify checkLinks from above to use raw Javascript:
function checkLinks( code, searchString )
{
var url;
// We need to create an HTML document element so we can use javascript dom functions on it.
var doc = document.createElement("html");
doc.innerHTML = code; // put the code into the document
// Get all links in the code
var links = doc.getElementsByTagName("a")
// Loop over all links
for (var i=0; i<links.length; i++) {
// Check if the search string (e.g "google.com") is found in the href of the link
if( links[i].getAttribute("href").indexOf(searchString) != -1 ) {
// Set it to the return value
url = links[i].getAttribute("href");
// stop looping
break;
}
}
return url;
}
So firstly, you need to set up the Ajax request object. The problem is this differs between browsers, so you need an unpleasant bit of code to generate it across them. The following is modified from the tiztag ajax tutorial:
function makeAJAXObject(){
var ajaxRequest; // The variable that makes Ajax possible!
try{
// Opera 8.0+, Firefox, Safari
ajaxRequest = new XMLHttpRequest();
} catch (e){
// Internet Explorer Browsers
try{
ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try{
ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e){
// Something went wrong
alert("Your browser broke!");
return false;
}
}
}
return ajaxRequest;
}
Ok, so now we've got our AJAX object, we want to get it to load a page, and tell it how to handle what we get back:
/*
* A function to load a given URL and process the code from it.
* It takes three arguments:
* php_handler The name of the PHP file that will load the code (or ASP, or whatever you choose to use)
* url The URL to be loaded.
* searchString The string to find in the links (e.g. "google.com").
*/
function load_page( php_handler, url, searchString )
{
// Get the ajax object using our function above.
window.ajax = makeAJAXObject( );
// Tell the AJAX object what to do when it's loaded the page
window.ajax.onreadystatechange = function(){
if(window.ajax.readyState == 4){ // 4 means it's loaded ok.
// For simplicity, I'll just alert this, but you would put your code to handle what to do when a match is found here.
alert(checkLinks( window.ajax.responseText, searchString ));
}
}
// Set up the variables you want to sent to your PHP page (namely, the URL of the page to load)
var queryString = "?url=" + url;
// Load the PHP script that opens the page
window.ajax.open("GET", php_handler + queryString, true);
window.ajax.send(null);
}
The final thing is to attach this to a button when the page has loaded:
window.onload = function( ) {
document.getElementById('linkchecker').onclick = function( ) {
load_page('load_page.php', 'http://www.example.com', 'google');
}
}
Please note, there's likely to be built in WinJS functions to handle some of the AJAX stuff, but I've never tried Win 8 app development, so I don't know them!
Related
I'm trying to intercept all AJAX calls in order to check if that AJAX response contains specific error code that I send as JSON from my PHP script (codes: ACCESS_DENIED, SYSTEM_ERROR, NOT_FOUND).
I know one can do something like this:
$('.log').ajaxSuccess(function(e, xhr, settings) {
});
But - does this work only if "ajaxSuccess" event bubble up to .log div? Am I correct? Can I achieve what I want by binding "ajaxSuccess" event to document?
$(document).ajaxSuccess(function(e, xhr, settings) {
});
I can do this in either jQuery or raw JavaScript.
If you're using jQuery, $.ajaxSuccess is a good option, but here's a generic option that will intercept XHR calls from all frameworks (I've tested it with ExtJS and jQuery - it should work even if multiple frameworks are loaded concurrently). It's been tested to work with IE8, Chrome and Firefox.
(function(XHR) {
"use strict";
var open = XHR.prototype.open;
var send = XHR.prototype.send;
XHR.prototype.open = function(method, url, async, user, pass) {
this._url = url;
open.call(this, method, url, async, user, pass);
};
XHR.prototype.send = function(data) {
var self = this;
var oldOnReadyStateChange;
var url = this._url;
function onReadyStateChange() {
if(self.readyState == 4 /* complete */) {
/* This is where you can put code that you want to execute post-complete*/
/* URL is kept in this._url */
}
if(oldOnReadyStateChange) {
oldOnReadyStateChange();
}
}
/* Set xhr.noIntercept to true to disable the interceptor for a particular call */
if(!this.noIntercept) {
if(this.addEventListener) {
this.addEventListener("readystatechange", onReadyStateChange, false);
} else {
oldOnReadyStateChange = this.onreadystatechange;
this.onreadystatechange = onReadyStateChange;
}
}
send.call(this, data);
}
})(XMLHttpRequest);
I've posted a more specific example on github which intercepts AJAX calls and posts the AJAX call durations back to the server for statistical analysis.
From http://api.jquery.com/ajaxSuccess/ :
Whenever an Ajax request completes successfully, jQuery triggers the ajaxSuccess event. Any and all handlers that have been registered with the .ajaxSuccess() method are executed at this time.
So the selector doesn't define the position where you are "catching" the event (because, honestly, ajax event by its nature doesn't start from a DOM element), but rather defines a scope to which the handling will be defaulted (i.e. this will poitn to that/those element(s)).
In summary - it should be exactly what you wish for
The best way, which I found https://lowrey.me/intercept-2/
const intercept = (urlmatch, callback) => {
let send = XMLHttpRequest.prototype.send;
XMLHttpRequest.prototype.send = function() {
this.addEventListener('readystatechange', function() {
if (this.responseURL.includes(urlmatch) && this.readyState === 4) {
callback(this);
}
}, false);
send.apply(this, arguments);
};
};
Try using Mockjax.js http://code.appendto.com/plugins/jquery-mockjax
It lets you hijack AJAX calls to the server and mock the location.
When Method of the senderform is POST, everything works fine. However, as soon as I change the method to GET, I don't receive anything on the server.
function ajaxSubmit(destinationElement, senderform) {
var xmlreq = new XMLHttpRequest();
var params = new FormData(senderform);
xmlreq.open(senderform.method, senderform.action, true);
if (/\/content\.php$/.test(senderform.action))
xmlreq.onreadystatechange = receiveTable;
else xmlreq.onreadystatechange = receiveText;
xmlreq.send(params);
}
I know that I could manually append key-value pairs at the end of Action address, but the problem is that I don't know which form is going to be passed with what fields.
I would prefer native javaScript if possible.
How can I send a GET request using XMLHttpRequest with key-value pairs from senderform which points to form Element (the same way as it already works for POST requests)?
First parameter is a reference to submit button, or form element itself. Second is callback function for XMLHttpRequest.
var ajaxSubmit = function(sender, callback) {
var xmlreq = new XMLHttpRequest(), params;
// look around for the sender form and key-value params
if (sender.form !== undefined)
{
params = new FormData(sender.form);
params.append(sender.name, sender.value);
sender = sender.form;
}
else params = new FormData(sender);
var actAddress = sender.action;
// append the params to the address in action attribute
if (sender.method == 'get')
{
var firstRun = true;
for (var key of params.keys())
{
if (firstRun)
{
actAddress += '?';
firstRun = false;
}
else actAddress += '&';
actAddress += key + "=" + params.get(key);
}
}
xmlreq.open(sender.method, actAddress, true);
xmlreq.onreadystatechange = callback;
if (sender.method == 'get')
xmlreq.send();
else xmlreq.send(params);
}
Therefore you can use it as
<form onsubmit="ajaxSubmit(this,callbackFx)" >
<!-- or -->
<input onclick="ajaxSubmit(this,callbackFx)" type="submit" name="" value=""/>
</form>
Are you sure the problem is not the PHP script? I see no reference that https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest#send() with FormData needs POST to work, but if the PHP script takes the info from $POST or something (My PHP is rusty), the behavior would be different.
Since you can't create a useable body in a GET request (see below), then the other option is to use params in the url.
function buildGetUrlParams(baseUrl, paramsObj) {
var builtUrl = baseUrl + "?";
Object.keys(paramsObj).forEach(function(key) {
builtUrl += key + "=" + paramsObj[key] + "&";
});
return builtUrl.substr(0, builtUrl.length - 1);
}
document.getElementById('finalUrl').innerText = buildGetUrlParams('http://test.url.com', { name:'James', occupation:'web design' });
<div id="finalUrl"></div>
An HTTP GET request can contain a body, but there is no semantic meaning to that body. Which means, in simple terms, that a server doesn't have any reason to, nor have any knowledge of how, to process the body of a GET request. If it's possible to write a server that could do this, it would be bad practice as per the HTTP/1.1 specs:
if the request method does not include defined semantics for an entity-body, then the message-body SHOULD be ignored when handling the request.
And that's basically why it's not working. If you want to send any sort of data that the server is able to respond to, then you'll need to use a different HTTP method.
This answer also explains this issue.
Hi I've been trying to clarify this but there's something I'm still confused about. I know that you can't return values from asynchronous functions so I've referenced this answer's top answer Returning value from asynchronous JavaScript method?
What I'm trying to do is use the flickrAPI to get the biggest size image. The flickrAPI allows one to search images, so I use this to get the photo_id, then I use this photo_id to procses another request to the API's getSize method to get the URL for the biggest size photo.
The code looks a little messy as it is, because I have a method called flickrRequest which sends an XMLHttp request and gets back a JSON string. I know that I can achieve what I want by writing the functions as follows:
function flickRQforimage() {
...got ID
function flickrRQforSize() {
...got maxsizeURL
create image based on maxsizeURL here
}
}
but I was wondering if it was possible to do something like this
function flickRQforimage() {
...got ID
function flickrRQforSize() {
...got maxsizeURL
}
create image based on maxsizeURL here
}
or even create image based on maxsizeURL here
In general my question is whether it is possible to have a callback function that references another statically defined function (I think?). The specifics of the my function is that it takes a callback and the ID and URL processing happens in those callbacks:
flickrRQ(options, cb)
I am wondering whether/what would happen if that unnamed function is instead something else, say flickrRQ(options, processPhoto(data)), and then I define the function in a separate method. This just makes sense for me because I want to keep functionality for the URL processing separate in an attempt to make my code cleaner and more readable.
I tried the following below and it didn't work. Nothing prints. I even have a console.log in the processPhoto method. In fact anything inside of the flickrRQforSize method seems to not evaluate
flickrRQforSize(options, function(data) {
processPhoto(data)
}
even though in the flickrRQforSize definition, a callback function is taken as an argument. I'm suspecting there must be something about functions/async calls that I don't understand.
I hope this is clear -- if not, I can post my actual code.
Here's my code:
var flickrRequest = function(options, xhrRQ, cb) {
var url, xhr, item, first;
url = "https://api.flickr.com/services/rest/";
first = true;
for (item in options) {
if (options.hasOwnProperty(item)) {
url += (first ? "?" : "&") + item + "=" + options[item];
//parses to search equest;
first = false;
}
}
//XMLHttpRQ to flickr
if(xhrRQ == 1 ) {
xhr = new XMLHttpRequest();
xhr.onload = function() { cb(this.response); };
xhr.open('get', url, true);
xhr.send();
};
}
var processPhotoSize = function(photoJSON) {
var parsedJSON = JSON.parse(data);
var last = parsedJSON.sizes.size.length;
console.log(parsedJSON.sizes.size[last-1].source);
return parsedJSON.sizes.size[last-1].source;
}
...
flickrRequest(options, 1, function(data) {
...
flickrRequest(sizesOptions, 0, function(data) {
parsedJSON = JSON.parse(data);
console.log(parsedJSON);
processPhotoSize(data);
});
}
I am working on a project that uses a function I called AjaxRequest which handles all AJAX requests I make. I have no problems in making the request however getting the request back is the issue and placing it where I want it on my page is becoming stressful.
HTML BIT
<body onLoad="calling();">
<div id="status">Status: </div>
</body>
JAVASCRIPT BIT
function calling() {
var answer = ajaxRequest("testing", "test.php", "test=test");
document.getElementById("status").innerHTML += answer[1];
document.getElementById("status").innerHTML += " " + answer[3];
}
function ajaxRequest(app, location, credentials) {
var extras = "";
if(credentials === "" || credentials) {
extras = "&" + credentials;
}
var ajax = ajaxObj("POST", location);
ajax.onreadystatechange = function() {
if(ajaxReturn(ajax) == true) {
var obj = JSON.parse(ajax.responseText);
var arrayObj = [];
for(var i in obj) { arrayObj.push([i, obj[i]]); }
return arrayObj;
}
}
ajax.send("app=" + app + extras);
}
there are two other functions running: ajaxObj and ajaxReturn but I excluded those because they is not the problem. Furthermore, I am trying to make ajaxRequest an efficient function that could be used by more than one application without having to rewrite all the code in more than one location. All error handling acquires before the actual use of ajaxRequest.
PHP BIT
<?php
if($_POST['app'] == "testing") {
$hey = array('success' => 1, 'message' => 'Successful');
echo json_encode($hey);
exit();
}
?>
I'm using calling as a javascript function that does all error handling, this is just basic for the whole of my project however I try to get the JSON from php and convert it to array and the issue is returning the array into calling. I try to display the information on the page yet nothing works.
I am not looking to use any JQuery for my project so I would like to exclude the use of it for this piece of code.
If you want, you could set the header before sending back the json.
header('Content-Type: application/json');
Usually you don't need it, but it will tell your javascript that it's json, and the array will be transform in a javascript object. It work with Jquery, but I assume it'll work without too
I have a JavaScript function that is being called. I need to have it call a PHP function and return a true/false.
The script with the function is in the file /db/cancel_hike.php
My current JS looks like this:
function uncancelHike( hike_id )
{
//var url = "/db/cancel_hike.php;
var success = null;
var request = window.ActiveXObject ?
new ActiveXObject('Microsoft.XMLHTTP') :
new XMLHttpRequest;
request.open("GET", url , true);
request.onreadystatechange = function()
{
if (request.readyState == 4)
{
var xmlDoc = request.responseXML;
// obtain the array of markers and loop through it
markers = xmlDoc.documentElement.getElementsByTagName("marker");
for (var i = 0; i < markers.length; i++)
{
// obtain the attribues of each marker
success = markers[i].getAttribute("success");
if ( success == "true" )
{
document.getElementById("success").style.display = 'block';
document.getElementById("warning").style.display = 'none';
document.getElementById("error").style.display = 'error';
}
if ( success == "false" )
{
document.getElementById("success").style.display = 'none';
document.getElementById("warning").style.display = 'none';
document.getElementById("error").style.display = 'block';
}
}
}
}
request.send(null);
return false;
}
What I am having trouble with is:
How to call an actual function in the PHP script?
Do I absolutely need to have some XML returned? Or is there a way to just get back the returned value?
I am using YUI JS library. Do I need to make some calls to it, or is it not necessary in this case?
How to call an actual function in the PHP script?
You can't. You request URIs.
Write a PHP script that calls the function you want and place it at the URI you call.
(You can use query strings and the like as the input to an if statement that you use to conditionally call different functions)
Do I absolutely need to have some XML returned? Or is there a way to just get back the returned value?
You can return any kind of data you like.
I am using YUI JS library. Do I need to make some calls to it, or is it not necessary in this case?
It's a library. You never need to make calls to it. It often simplifies the code you have to write.
How to call an actual function in the PHP script?
Do I absolutely need to have some XML returned? Or is there a way to just get back the returned value?
Well, you don't call the actual function. What you want to do is pass variables using GET, that is, by appending them to the URL like file_name.php?var1=this&var2=that to pass var1 of "this" and var2 equaling "that." You retrieve them in the PHP file with $_GET['this'] and $_GET['that']. Whatever PHP outputs to the page via echo, print_r, etc. is then sent back in a request object as part of its responseText property.
You just set url in request.open to a URL on your site. For example, in your .js file:
request.open("GET", "answer_me.php?hike_id=" + hike_id, true);
And in your .php file:
<?php
$hike_id = $_GET['hike_id'];
if ($hike_id < 5) {
echo "true"; // echo true would return "1", BTW
} else {
echo "false"; // echo false would return nothing
}
Note that that will just return a string value to request.responseText of false, thus you could do this:
var result = request.responseText;
if (result === "true") {
...
document.getElementById("success").style.display = "block";
...
} else {
...
document.getElementById("success").style.display = "none";
...
}
You do not need it to be XML, especially as it looks like you're not really using the loop (the same three DOM elements are being assigned values each time).
And honestly, for AJAX I'd recommend using a framework like jQuery (or YUI, although I don't find its AJAX stuff as intuitive). Your entire code would look like this:
var $success = $("#success");
var $error = $("#error");
function cancelHikeCallback(data) {
var is_success = (data === "true");
$success.toggle(is_success);
$error.toggle(!is_success);
}
function cancelHike(hikeIdToSend) {
$.get("/db/cancel_hike.php", {hike_id: hikeIdToSend}, cancelHikeCallback);
}
IMO things like jQuery's $.ajax ($.get is a specialized form of $.ajax) make this stuff much easier to read and debug.
jsFiddle Example