I'm trying to teach myself how to write Chrome extensions and ran into a snag when I realized that my jQuery was breaking because it was getting information from the extension page itself and not the tab's current page like I had expected.
Quick summary, my sample extension will refresh the page every x seconds, look at the contents/DOM, and then do some stuff with it. The first and last parts are fine, but getting the DOM from the page that I'm on has proven very difficult, and the documentation hasn't been terribly helpful for me.
You can see the code that I have so far at these links:
Current manifest
Current js script
Current popup.html
If I want to have the ability to grab the DOM on each cycle of my setInterval call, what more needs to be done? I know that, for example, I'll need to have a content script. But do I also need to specify a background page in my manifest? Where do I need to call the content script within my extension? What's the easiest/best way to have it communicate with my current js file on each reload? Will my content script also be expecting me to use jQuery?
I know that these questions are basic and will seem trivial to me in retrospect, but they've really been a headache trying to explore completely on my own. Thanks in advance.
In order to access the web-pages DOM you'll need to programmatically inject some code into it (using chrome.tabs.executeScript()).
That said, although it is possible to grab the DOM as a string, pass it back to your popup, load it into a new element and look for what ever you want, this is a really bad approach (for various reasons).
The best option (in terms of efficiency and accuracy) is to do the processing in web-page itself and then pass just the results back to the popup. Note that in order to be able to inject code into a web-page, you have to include the corresponding host match pattern in your permissions property in manifest.
What I describe above can be achieved like this:
editorMarket.js
var refresherID = 0;
var currentID = 0;
$(document).ready(function(){
$('.start-button').click(function(){
oldGroupedHTML = null;
oldIndividualHTML = null;
chrome.tabs.query({ active: true }, function(tabs) {
if (tabs.length === 0) {
return;
}
currentID = tabs[0].id;
refresherID = setInterval(function() {
chrome.tabs.reload(currentID, { bypassCache: true }, function() {
chrome.tabs.executeScript(currentID, {
file: 'content.js',
runAt: 'document_idle',
allFrames: false
}, function(results) {
if (chrome.runtime.lastError) {
alert('ERROR:\n' + chrome.runtime.lastError.message);
return;
} else if (results.length === 0) {
alert('ERROR: No results !');
return;
}
var nIndyJobs = results[0].nIndyJobs;
var nGroupJobs = results[0].nGroupJobs;
$('.lt').text('Indy: ' + nIndyJobs + '; '
+ 'Grouped: ' + nGroupJobs);
});
});
}, 5000);
});
});
$('.stop-button').click(function(){
clearInterval(refresherID);
});
});
content.js:
(function() {
function getNumberOfIndividualJobs() {...}
function getNumberOfGroupedJobs() {...}
function comparator(grouped, individual) {
var IndyJobs = getNumberOfIndividualJobs();
var GroupJobs = getNumberOfGroupedJobs();
nIndyJobs = IndyJobs[1];
nGroupJobs = GroupJobs[1];
console.log(GroupJobs);
return {
nIndyJobs: nIndyJobs,
nGroupJobs: nGroupJobs
};
}
var currentGroupedHTML = $(".grouped_jobs").html();
var currentIndividualHTML = $(".individual_jobs").html();
var result = comparator(currentGroupedHTML, currentIndividualHTML);
return result;
})();
I have been searching how to put more than one function in onchange and I found how something like this for example: onchange = "function1(); function2();".
My problem here is I have followed what does the example like, but only function1 is working, function2 is not working. If I make it otherwise to onchange = "function2(); function1();", only function2 is working, function1 is not working, the same.
Any ideas guys?
Thanks.
The functions, I used Ajax:
function1(test)
{
var kode = test.value;
if (!kode) return;
xmlhttp.open('get', '../template/get_name-opr.php?kode='+kode, true);
xmlhttp.onreadystatechange = function() {
if ((xmlhttp.readyState == 4) && (xmlhttp.status == 200))
{
//alert(kode);
document.getElementById("code").innerHTML = xmlhttp.responseText;
}
return false;
}
xmlhttp.send(null);
}
function2(test)
{
var kode = test.value;
if (!kode) return;
xmlhttp**1**.open('get', '../template/get_name2-opr.php?kode='+kode, true);
xmlhttp**1**.onreadystatechange = function() {
if ((xmlhttp**1**.readyState == 4) && (xmlhttp**1**.status == 200))
{
//alert(kode);
document.getElementById("code2").innerHTML = xmlhttp**1**.responseText;
}
return false;
}
xmlhttp**1**.send(null);
}
To solve my problem, I created two xmlhttp different. (xmlhttp and xmlhttp1).
Go through the link I gave, it seems to be problem with the way you are managing the xmlhttprequest objects, manage their instances properly, in your case because you are using the same xmlhttprequest for two simultaneous AJAX requests, only one of them is getting served. Either wait for one of them to get served or create two instances of the xmlhttprequest.
The statement xmlhttp.readystate = function() {...} obviously replaces the readystate property of that xmlhttprequest object, so on your second function, that is being replaced( because you are using the xmlhttprequest for both of them ). This is why you are seeing the funny behaviour.
Call function2() at the end of function1().
onchange = "function1()"
function1(){
...
function1 body;
...
function2()
}
Wrap the two function calls in one and call that function!
function myFirstFunction() {
//body
}
function mySecondFunction() {
//body
}
//Call this guy.
function myWrappedFunction() {
myFirstFunction();
mySecondFunction();
}
Hi there i have this code snippet I need to get working with MooTools 1.3 :
this.fn = function (e, cal) {
var e = new Event(e);
var el = e.target;
var stop = false;
while (el != document.body && el.nodeType == 1) {
if (el == this.calendar) { stop = true; }
this.calendars.each(function (kal) {
if (kal.button == el || kal.els.contains(el)) { stop = true; }
});
if (stop) {
e.stop();
return false;
}
else { el = el.parentNode; }
}
this.toggle(cal);
}.create({
'arguments': cal,
'bind': this,
'event': true
}); <-- THIS CREATE METHOD DOES NOT WORK
Can someone help me whit this ?
After create function was deprecated, you need to "manually" recreate the usage.
In this case, you are creating a function that will be an event listener and binding it later in the code (this is Aeron Glemann's calendar).
So what you need to do, is put this function in addEvent you find directly below it, like this.
document.addEvent('mousedown', function(e, cal) {
[...]
}.bind(this));
Also, there's a removeEvent call at the begining of the function you're currently editing (the toggle function) that will no longer work since this function no longer has a name, replace it with removing all events on mousedown, worked for me.
document.removeEvents('mousedown');
as i said on the mootools user mailing list, i don't know about the "perfect" way, but in the meantime you can always (if you don't want to use the 1.2 compat version)
inspire yourself from the implementation of the function for 1.2 compat :
https://github.com/mootools/mootools-core/blob/025adc07dc7e9851f30b3911961d43d525d83847/Source/Types/Function.js#L74
I have to admit the doc for 1.3 only mention that this method is deprecated.
I'd like to be able to highlight the drop area as soon as the cursor carrying a file enters the browser window, exactly the way Gmail does it. But I can't make it work, and I feel like I'm just missing something really obvious.
I keep trying to do something like this:
this.body = $('body').get(0)
this.body.addEventListener("dragenter", this.dragenter, true)
this.body.addEventListener("dragleave", this.dragleave, true)`
But that fires the events whenever the cursor moves over and out of elements other than BODY, which makes sense, but absolutely doesn't work. I could place an element on top of everything, covering the entire window and detect on that, but that'd be a horrible way to go about it.
What am I missing?
I solved it with a timeout (not squeaky-clean, but works):
var dropTarget = $('.dropTarget'),
html = $('html'),
showDrag = false,
timeout = -1;
html.bind('dragenter', function () {
dropTarget.addClass('dragging');
showDrag = true;
});
html.bind('dragover', function(){
showDrag = true;
});
html.bind('dragleave', function (e) {
showDrag = false;
clearTimeout( timeout );
timeout = setTimeout( function(){
if( !showDrag ){ dropTarget.removeClass('dragging'); }
}, 200 );
});
My example uses jQuery, but it's not necessary. Here's a summary of what's going on:
Set a flag (showDrag) to true on dragenter and dragover of the html (or body) element.
On dragleave set the flag to false. Then set a brief timeout to check if the flag is still false.
Ideally, keep track of the timeout and clear it before setting the next one.
This way, each dragleave event gives the DOM enough time for a new dragover event to reset the flag. The real, final dragleave that we care about will see that the flag is still false.
Modified version from Rehmat (thx)
I liked this idea and instead of writing a new answer, I am updating it here itself. It can be made more precise by checking window dimensions.
var body = document.querySelector("body");
body.ondragleave = (e) => {
if (
e.clientX >= 0 && e.clientX <= body.clientWidth
&& e.clientY >= 0 && e.clientY <= body.clientHeight
) {} else {
// do something here
}
}
Old Version
Don't know it this works for all cases but in my case it worked very well
$('body').bind("dragleave", function(e) {
if (!e.originalEvent.clientX && !e.originalEvent.clientY) {
//outside body / window
}
});
Adding the events to document seemed to work? Tested with Chrome, Firefox, IE 10.
The first element that gets the event is <html>, which should be ok I think.
var dragCount = 0,
dropzone = document.getElementById('dropzone');
function dragenterDragleave(e) {
e.preventDefault();
dragCount += (e.type === "dragenter" ? 1 : -1);
if (dragCount === 1) {
dropzone.classList.add('drag-highlight');
} else if (dragCount === 0) {
dropzone.classList.remove('drag-highlight');
}
};
document.addEventListener("dragenter", dragenterDragleave);
document.addEventListener("dragleave", dragenterDragleave);
Here's another solution. I wrote it in React, but I'll explain it at the end if you want to rebuild it in plain JS. It's similar to other answers here, but perhaps slightly more refined.
import React from 'react';
import styled from '#emotion/styled';
import BodyEnd from "./BodyEnd";
const DropTarget = styled.div`
position: fixed;
top: 0;
right: 0;
bottom: 0;
left: 0;
pointer-events: none;
background-color:rgba(0,0,0,.5);
`;
function addEventListener<K extends keyof DocumentEventMap>(type: K, listener: (this: Document, ev: DocumentEventMap[K]) => any, options?: boolean | AddEventListenerOptions) {
document.addEventListener(type, listener, options);
return () => document.removeEventListener(type, listener, options);
}
function setImmediate(callback: (...args: any[]) => void, ...args: any[]) {
let cancelled = false;
Promise.resolve().then(() => cancelled || callback(...args));
return () => {
cancelled = true;
};
}
function noop(){}
function handleDragOver(ev: DragEvent) {
ev.preventDefault();
ev.dataTransfer!.dropEffect = 'copy';
}
export default class FileDrop extends React.Component {
private listeners: Array<() => void> = [];
state = {
dragging: false,
}
componentDidMount(): void {
let count = 0;
let cancelImmediate = noop;
this.listeners = [
addEventListener('dragover',handleDragOver),
addEventListener('dragenter',ev => {
ev.preventDefault();
if(count === 0) {
this.setState({dragging: true})
}
++count;
}),
addEventListener('dragleave',ev => {
ev.preventDefault();
cancelImmediate = setImmediate(() => {
--count;
if(count === 0) {
this.setState({dragging: false})
}
})
}),
addEventListener('drop',ev => {
ev.preventDefault();
cancelImmediate();
if(count > 0) {
count = 0;
this.setState({dragging: false})
}
}),
]
}
componentWillUnmount(): void {
this.listeners.forEach(f => f());
}
render() {
return this.state.dragging ? <BodyEnd><DropTarget/></BodyEnd> : null;
}
}
So, as others have observed, the dragleave event fires before the next dragenter fires, which means our counter will momentarily hit 0 as we drag files (or whatever) around the page. To prevent that, I've used setImmediate to push the event to the bottom of JavaScript's event queue.
setImmediate isn't well supported, so I wrote my own version which I like better anyway. I haven't seen anyone else implement it quite like this. I use Promise.resolve().then to move the callback to the next tick. This is faster than setImmediate(..., 0) and simpler than many of the other hacks I've seen.
Then the other "trick" I do is to clear/cancel the leave event callback when you drop a file just in case we had a callback pending -- this will prevent the counter from going into the negatives and messing everything up.
That's it. Seems to work very well in my initial testing. No delays, no flashing of my drop target.
Can get the file count too with ev.dataTransfer.items.length
#tyler's answer is the best! I have upvoted it. After spending so many hours I got that suggestion working exactly as intended.
$(document).on('dragstart dragenter dragover', function(event) {
// Only file drag-n-drops allowed, http://jsfiddle.net/guYWx/16/
if ($.inArray('Files', event.originalEvent.dataTransfer.types) > -1) {
// Needed to allow effectAllowed, dropEffect to take effect
event.stopPropagation();
// Needed to allow effectAllowed, dropEffect to take effect
event.preventDefault();
$('.dropzone').addClass('dropzone-hilight').show(); // Hilight the drop zone
dropZoneVisible= true;
// http://www.html5rocks.com/en/tutorials/dnd/basics/
// http://api.jquery.com/category/events/event-object/
event.originalEvent.dataTransfer.effectAllowed= 'none';
event.originalEvent.dataTransfer.dropEffect= 'none';
// .dropzone .message
if($(event.target).hasClass('dropzone') || $(event.target).hasClass('message')) {
event.originalEvent.dataTransfer.effectAllowed= 'copyMove';
event.originalEvent.dataTransfer.dropEffect= 'move';
}
}
}).on('drop dragleave dragend', function (event) {
dropZoneVisible= false;
clearTimeout(dropZoneTimer);
dropZoneTimer= setTimeout( function(){
if( !dropZoneVisible ) {
$('.dropzone').hide().removeClass('dropzone-hilight');
}
}, dropZoneHideDelay); // dropZoneHideDelay= 70, but anything above 50 is better
});
Your third argument to addEventListener is true, which makes the listener run during capture phase (see http://www.w3.org/TR/DOM-Level-3-Events/#event-flow for a visualization). This means that it will capture the events intended for its descendants - and for the body that means all elements on the page. In your handlers, you'll have to check if the element they're triggered for is the body itself. I'll give you my very dirty way of doing it. If anyone knows a simpler way that actually compares elements, I'd love to see it.
this.dragenter = function() {
if ($('body').not(this).length != 0) return;
... functional code ...
}
This finds the body and removes this from the set of elements found. If the set isn't empty, this wasn't the body, so we don't like this and return. If this is body, the set will be empty and the code executes.
You can try with a simple if (this == $('body').get(0)), but that will probably fail miserably.
I was having trouble with this myself and came up with a usable solution, though I'm not crazy about having to use an overlay.
Add ondragover, ondragleave and ondrop to window
Add ondragenter, ondragleave and ondrop to an overlay and a target element
If drop occurs on the window or overlay, it is ignored, whereas the target handles the drop as desired. The reason we need an overlay is because ondragleave triggers every time an element is hovered, so the overlay prevents that from happening, while the drop zone is given a higher z-index so that the files can be dropped. I am using some code snippets found in other drag and drop related questions, so I cannot take full credit. Here's the full HTML:
<!DOCTYPE html>
<html>
<head>
<title>Drag and Drop Test</title>
<meta http-equiv="X-UA-Compatible" content="chrome=1" />
<style>
#overlay {
display: none;
left: 0;
position: absolute;
top: 0;
z-index: 100;
}
#drop-zone {
background-color: #e0e9f1;
display: none;
font-size: 2em;
padding: 10px 0;
position: relative;
text-align: center;
z-index: 150;
}
#drop-zone.hover {
background-color: #b1c9dd;
}
output {
bottom: 10px;
left: 10px;
position: absolute;
}
</style>
<script>
var windowInitialized = false;
var overlayInitialized = false;
var dropZoneInitialized = false;
function handleFileSelect(e) {
e.preventDefault();
var files = e.dataTransfer.files;
var output = [];
for (var i = 0; i < files.length; i++) {
output.push('<li>',
'<strong>', escape(files[i].name), '</strong> (', files[i].type || 'n/a', ') - ',
files[i].size, ' bytes, last modified: ',
files[i].lastModifiedDate ? files[i].lastModifiedDate.toLocaleDateString() : 'n/a',
'</li>');
}
document.getElementById('list').innerHTML = '<ul>' + output.join('') + '</ul>';
}
window.onload = function () {
var overlay = document.getElementById('overlay');
var dropZone = document.getElementById('drop-zone');
dropZone.ondragenter = function () {
dropZoneInitialized = true;
dropZone.className = 'hover';
};
dropZone.ondragleave = function () {
dropZoneInitialized = false;
dropZone.className = '';
};
dropZone.ondrop = function (e) {
handleFileSelect(e);
dropZoneInitialized = false;
dropZone.className = '';
};
overlay.style.width = (window.innerWidth || document.body.clientWidth) + 'px';
overlay.style.height = (window.innerHeight || document.body.clientHeight) + 'px';
overlay.ondragenter = function () {
if (overlayInitialized) {
return;
}
overlayInitialized = true;
};
overlay.ondragleave = function () {
if (!dropZoneInitialized) {
dropZone.style.display = 'none';
}
overlayInitialized = false;
};
overlay.ondrop = function (e) {
e.preventDefault();
dropZone.style.display = 'none';
};
window.ondragover = function (e) {
e.preventDefault();
if (windowInitialized) {
return;
}
windowInitialized = true;
overlay.style.display = 'block';
dropZone.style.display = 'block';
};
window.ondragleave = function () {
if (!overlayInitialized && !dropZoneInitialized) {
windowInitialized = false;
overlay.style.display = 'none';
dropZone.style.display = 'none';
}
};
window.ondrop = function (e) {
e.preventDefault();
windowInitialized = false;
overlayInitialized = false;
dropZoneInitialized = false;
overlay.style.display = 'none';
dropZone.style.display = 'none';
};
};
</script>
</head>
<body>
<div id="overlay"></div>
<div id="drop-zone">Drop files here</div>
<output id="list"><output>
</body>
</html>
I see a lot of overengineered solutions out there. You should be able to achieve this by simply listening to dragenter and dragleave as your gut seemingly told you.
The tricky part is that when dragleave fires, it seems to have its toElement and fromElement inverted from what makes sense in everyday life (which kind of makes sense in logical terms since it's the inverted action of dragenter).
Bottom-line when you move the cursor from the listening element to outside that element, toElement will have the listening element and fromElement will have the outer non-listening element. In our case, fromElement will be null when we drag outside the browser.
Solution
window.addEventListener("dragleave", function(e){
if (!e.fromElement){
console.log("Dragging back to OS")
}
})
window.addEventListener("dragenter", function(e){
console.log("Dragging to browser")
})
The ondragenter is fired quite often. You can avoid using a helper variable like draggedFile. If you don't care how often your on ondragenter function is being called, you can remove that helper variable.
Solution:
let draggedFile = false;
window.ondragenter = (e) => {
if(!draggedFile) {
draggedFile = true;
console.log("dragenter");
}
}
window.ondragleave = (e) => {
if (!e.fromElement && draggedFile) {
draggedFile = false;
console.log("dragleave");
}
}
Have you noticed that there is a delay before the dropzone disappears in Gmail? My guess is that they have it disappear on a timer (~500ms) that gets reset by dragover or some such event.
The core of the problem you described is that dragleave is triggered even when you drag into a child element. I'm trying to find a way to detect this, but I don't have an elegantly clean solution yet.
really sorry to post something that is angular & underscore specific, however the way i solved the problem (HTML5 spec, works on chrome) should be easy to observe.
.directive('documentDragAndDropTrigger', function(){
return{
controller: function($scope, $document){
$scope.drag_and_drop = {};
function set_document_drag_state(state){
$scope.$apply(function(){
if(state){
$document.context.body.classList.add("drag-over");
$scope.drag_and_drop.external_dragging = true;
}
else{
$document.context.body.classList.remove("drag-over");
$scope.drag_and_drop.external_dragging = false;
}
});
}
var drag_enters = [];
function reset_drag(){
drag_enters = [];
set_document_drag_state(false);
}
function drag_enters_push(event){
var element = event.target;
drag_enters.push(element);
set_document_drag_state(true);
}
function drag_leaves_push(event){
var element = event.target;
var position_in_drag_enter = _.find(drag_enters, _.partial(_.isEqual, element));
if(!_.isUndefined(position_in_drag_enter)){
drag_enters.splice(position_in_drag_enter,1);
}
if(_.isEmpty(drag_enters)){
set_document_drag_state(false);
}
}
$document.bind("dragenter",function(event){
console.log("enter", "doc","drag", event);
drag_enters_push(event);
});
$document.bind("dragleave",function(event){
console.log("leave", "doc", "drag", event);
drag_leaves_push(event);
console.log(drag_enters.length);
});
$document.bind("drop",function(event){
reset_drag();
console.log("drop","doc", "drag",event);
});
}
};
})
I use a list to represent the elements that have triggered a drag enter event. when a drag leave event happens i find the element in the drag enter list that matches, remove it from the list, and if the resulting list is empty i know that i have dragged outside of the document/window.
I need to reset the list containing dragged over elements after a drop event occurs, or the next time I start dragging something the list will be populated with elements from the last drag and drop action.
I have only tested this on chrome so far. I made this because Firefox and chrome have different API implementations of HTML5 DND. (drag and drop).
really hope this helps some people.
When the file enters and leaves child elements it fires additional dragenter and dragleave so you need to count up and down.
var count = 0
document.addEventListener("dragenter", function() {
if (count === 0) {
setActive()
}
count++
})
document.addEventListener("dragleave", function() {
count--
if (count === 0) {
setInactive()
}
})
document.addEventListener("drop", function() {
if (count > 0) {
setInactive()
}
count = 0
})
I found out from looking at the spec that if the evt.dataTransfer.dropEffect on dragEnd match none then it's a cancelation.
I did already use that event to handle copying without affecting the clipboard. so this was good for me.
When I hit Esc then the drop effect was equal to none
window.ondragend = evt => {
if (evt.dataTransfer.dropEffect === 'none') abort
if (evt.dataTransfer.dropEffect === 'copy') copy // user holds alt on mac
if (evt.dataTransfer.dropEffect === 'move') move
}
on "dropend" event you can check the value of the document.focus() was the magic trick in my case.