Develop Reference

JQuery call popup

I am an Apprentice and never worked with Javascript.
My Javascript function calls a popup. This works on the first button but doesn't work on all the following and since the application is constantly adding buttons(same class) I cannot hardcode. I guess ther will be a solution with JQuery...
("open") and ("openPopupUseExisting") are the two buttons.
<script type="text/javascript">
window.onload = function () {
document.getElementById('blackout').addEventListener('click', function () {
document.getElementById('popup').className = "";
document.getElementById('blackout').className = "";
document.getElementById('popupUseExisting').className = "";
}, false);
document.getElementsByClassName("open")[0].addEventListener('click', function () {
document.getElementById('popup').className = 'visable';
document.getElementById('blackout').className = 'visable';
}, false);
document.getElementsByClassName("openPopupUseExisting")[0].addEventListener('click', function () {
document.getElementById('popupUseExisting').className = 'visable';
document.getElementById('blackout').className = 'visable';
}, false);
document.getElementsByClassName("close")[0].addEventListener('click', function () {
document.getElementById('popup').className = "";
document.getElementById('blackout').className = "";
document.getElementById('popupUseExisting').className = "";
}, false);
};
</script>

document.getElementsByClassName("close")[0]
See that 0?
getElementsByClassName returns an array-like object. You are getting the first item off it.
Loop over it with a for loop.

Friend, you don't need to add an entire library just in order to bind dynamically added elements.
You can bind the document for click event, and then check if the clicked element is the one you want. It prevent dynamically added elements to be unbound, since it aims for the entire document.
document.addEventListener('click', function (e) {
if (e.target.classList.contains('blackout')) {
// your fancy magic with .blackout
} else if (e.target.classList.contains('open')) {
// your fancy magic with .open
}
}, false);
If you really want to use jQuery, as you ordered, it's quite simple, use the on method
$('.open').on('click', function(){
// your fancy magic with .open
});

Passing parameters to a event listener function in javascript

Hello I have some code in which I take user input through in html and assign it to,two global variables
var spursscoref = document.getElementById("spursscore").value;
var livscoref = document.getElementById("livscore").value;
Which next show up in this addeventlistener function as parameters of the whowon function
var d = document.querySelector("#gut2");
d.addEventListener("click", function () {
whowon(spursscoref, livscoref, spurs, liverpool)
}, false);
The click event is meant to trigger the whowon function and pass in the parameters
function whowon(FirstScore, SecondScore, FirstTeam, SecondTeam) {
if (FirstScore > SecondScore) {
FirstTeam.win();
SecondTeam.lose();
} else if (FirstScore < SecondScore) {
SecondTeam.win();
} else {
FirstTeam.draw();
SecondTeam.draw();
}
}
However the values are null,as I get a cannot read properties of null error on this line
var spursscoref = document.getElementById("spursscore").value;
I am pretty sure the problem is coming from the addlistener function,any help would be appreciated

Well you could do something like this -
$( document ).ready(function() {
var d = document.querySelector("#gut2");
d.addEventListener("click", function () {
var spursscoref = document.getElementById("spursscore").value;
var livscoref = document.getElementById("livscore").value;
whowon(spursscoref, livscoref, spurs, liverpool)
}, false);
});
Wrap your code in $(document).ready(function(){}). This will ensure that all of your DOM elements are loaded prior to executing your Javascript code.

Try putting all of your code inside this
document.addEventListener("DOMContentLoaded", function(event) {
//Your code here
});
My guess is that your code is executed before the html actually finished loading, causing it to return null.

how to get javaScript event source element?

Is there a way to retrieve the element source of an inline javaScript call?
I have a button like this:
<button onclick="doSomething('param')" id="id_button">action</button>
Note:
the button is generated from server
I cannot modify the generation process
several buttons are generated on the page, I have control only on client side.
What I have tried:
function doSomething(param){
var source = event.target || event.srcElement;
console.log(source);
}
On firebug I get event is not defined
Edit:
After some answers, an override of the event handling using jQuery is very acceptable. My issue is how to call the original onClick function with it's original prameters, and without knowing the function name.
code:
<button onclick="doSomething('param')" id="id_button1">action1</button>
<button onclick="doAnotherSomething('param1', 'param2')" id="id_button1">action2</button>.
<button onclick="doDifferentThing()" id="id_button3">action3</button>
.
.
and so on..
So the override would be:
$(document).on('click', 'button', function(e) {
e.preventDefault();
var action = $(this).attr('onclick');
/**
* What to do here to call
* - doSomething(this, 'param'); if button1 is clicked
* - doAnotherSomething(this, 'param1', 'param2'); if button2 is clicked
* - doDifferentThing(this); if button3 is clicked
* there are many buttons with many functions..
*/
});

Your html should be like this:
<button onclick="doSomething" id="id_button">action</button>
And renaming your input-paramter to event like this
function doSomething(event){
var source = event.target || event.srcElement;
console.log(source);
}
would solve your problem.
As a side note, I'd suggest taking a look at jQuery and unobtrusive javascript

You should change the generated HTML to not use inline javascript, and use addEventListener instead.
If you can not in any way change the HTML, you could get the onclick attributes, the functions and arguments used, and "convert" it to unobtrusive javascript instead by removing the onclick handlers, and using event listeners.
We'd start by getting the values from the attributes
$('button').each(function(i, el) {
var funcs = [];
$(el).attr('onclick').split(';').map(function(item) {
var fn = item.split('(').shift(),
params = item.match(/\(([^)]+)\)/),
args;
if (params && params.length) {
args = params[1].split(',');
if (args && args.length) {
args = args.map(function(par) {
return par.trim().replace(/('")/g,"");
});
}
}
funcs.push([fn, args||[]]);
});
$(el).data('args', funcs); // store in jQuery's $.data
console.log( $(el).data('args') );
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button onclick="doSomething('param')" id="id_button1">action1</button>
<button onclick="doAnotherSomething('param1', 'param2')" id="id_button1">action2</button>.
<button onclick="doDifferentThing()" id="id_button3">action3</button>
That gives us an array of all and any global methods called by the onclick attribute, and the arguments passed, so we can replicate it.
Then we'd just remove all the inline javascript handlers
$('button').removeAttr('onclick')
and attach our own handlers
$('button').on('click', function() {...}
Inside those handlers we'd get the stored original function calls and their arguments, and call them.
As we know any function called by inline javascript are global, we can call them with window[functionName].apply(this-value, argumentsArray), so
$('button').on('click', function() {
var element = this;
$.each(($(this).data('args') || []), function(_,fn) {
if (fn[0] in window) window[fn[0]].apply(element, fn[1]);
});
});
And inside that click handler we can add anything we want before or after the original functions are called.
A working example
$('button').each(function(i, el) {
var funcs = [];
$(el).attr('onclick').split(';').map(function(item) {
var fn = item.split('(').shift(),
params = item.match(/\(([^)]+)\)/),
args;
if (params && params.length) {
args = params[1].split(',');
if (args && args.length) {
args = args.map(function(par) {
return par.trim().replace(/('")/g,"");
});
}
}
funcs.push([fn, args||[]]);
});
$(el).data('args', funcs);
}).removeAttr('onclick').on('click', function() {
console.log('click handler for : ' + this.id);
var element = this;
$.each(($(this).data('args') || []), function(_,fn) {
if (fn[0] in window) window[fn[0]].apply(element, fn[1]);
});
console.log('after function call --------');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button onclick="doSomething('param');" id="id_button1">action1</button>
<button onclick="doAnotherSomething('param1', 'param2')" id="id_button2">action2</button>.
<button onclick="doDifferentThing()" id="id_button3">action3</button>
<script>
function doSomething(arg) { console.log('doSomething', arg) }
function doAnotherSomething(arg1, arg2) { console.log('doAnotherSomething', arg1, arg2) }
function doDifferentThing() { console.log('doDifferentThing','no arguments') }
</script>

Cross-Browser solution
I believe the solution by #slipset was correct, and it doesn't need jQuery, BUT it wasn't cross-browser ready.
According to Javascript.info, events (when referenced outside markup events) are cross-browser ready once you assure it's defined with this simple line: event = event || window.event.
So the complete cross-browser ready function would look like this:
function logMySource(param){
event = event || window.event;
var source = event.target || event.srcElement;
console.log("sourceID= "+source.id,"\nsourceTagName= "+source.tagName,"\nparam= "+param);
}
<button onclick="logMySource('myVariable')" id="myID">action</button>
Try it!
I've included returns of useful information of the source.

You can pass this when you call the function
<button onclick="doSomething('param',this)" id="id_button">action</button>
<script>
function doSomething(param,me){
var source = me
console.log(source);
}
</script>

Try something like this:
<html>
<body>
<script type="text/javascript">
function doSomething(event) {
var source = event.target || event.srcElement;
console.log(source);
alert('test');
if(window.event) {
// IE8 and earlier
// doSomething
} else if(e.which) {
// IE9/Firefox/Chrome/Opera/Safari
// doSomething
}
}
</script>
<button onclick="doSomething('param')" id="id_button">
action
</button>
</body>
</html>

USE .live()
$(selector).live(events, data, handler);
As of jQuery 1.7, the .live() method is deprecated. Use .on() to attach event handlers.
$(document).on(events, selector, data, handler);

Google Apps Script Find function caller id

I have a Google Apps Script that dynamically generates buttons and assigns for each a ClickHandler which in turn calls a function.
My problem is that because every button calls the same function I can't find a way to indentify which of them actually made the call. Here is a code sample:
var handler = app.createServerHandler("buttonAction");
for (i=1,...) {
app.createButton(...).setId(i).addClickHandler(handler);
}
function buttonAction() {
//How do I know what button made the call?
}

Another option is to use the e.parameter.source value to determine the ID of the element that triggered the serverHandler to be called.
Here's an example:
function doGet(e) {
var app = UiApp.createApplication();
var handler = app.createServerHandler("buttonAction");
for (var i = 0; i < 4; i++) {
app.add(app.createButton('button'+i).setId(i).addClickHandler(handler));
}
return app;
}
function buttonAction(e) {
var app = UiApp.getActiveApplication();
Logger.log(e.parameter.source);
}
e.parameter.source will contain the ID of the element, which you could then use to call app.getElementById(e.parameter.source) ...

You could create multiple handlers, each for one button:
for (i=1,...) {
var handler = app.createServerHandler("buttonAction" + i);
app.createButton(...).setId(i).addClickHandler(handler);
}
function buttonAction1() {
// code to handle button 1
}
function buttonAction2() {
// code to handle button 2
}
function buttonAction...
I wouldn't recommend of having these sort of "anonymous" action handlers though, as you might be having troubles later in remembering which actionX does what.
(e.g. have a different approach, w/o a loop, or prepare a dictionary-like/array object of meaningful handler names before that loop.)
OTOH, you could use event object argument provided to your callback function:
function buttonAction(event) {
// use event object here to identify where this event came from
}
The thing is the above event object properties depends on where your callback is being called from. For instance, if it were a submit button where you had a Form, then you could access parameters submitted by that from like so: event.parameter.myParamName. See code sample here.
So, if you have a variable number of buttons, you could use a hidden element + the button:
for (i=1,...) {
var hiddenAction = app.createHidden("action", "action"+i);
var handler = app.createServerHandler("buttonAction");
handler.addCallbackElement(hiddenAction);
var btn = app.createButton("Button text", handler);
// you'll need to add both btn and hidden field
// to the UI
app.add(hiddenAction);
app.add(btn);
}
Then, your buttonAction might look like this:
function buttonAction(e) {
var action = e.parameter.action;
// do something based on action value here
// which will be one of "action1", "action2", ...
}
The above is a copy & paste from Hidden class sample.
The above might not work out of the box, but you get the idea: create a hidden element that holds the info you need in your callback, and attach that hidden to your server handler. You could even create multiple hidden elements or a Form panel.

I have the same issue. It works using Tag.
EG
SETUP
var button = addButton(app
,panel
,"buttonActiveTrelloProjects_" + i.toString()
,appVars.buttonWidth() + "px"
,appVars.level2ButtonHeight().toString() + "px"
,false
,false
,"Trello"
,"buttonActiveTrelloProjectsHandler"
,(appVars.buttonLhsGap() * buttonCntr) + (appVars.buttonWidth() * (buttonCntr - 1 ) + 9)
,(appVars.level2ButtonTopGap() * 34)
,3
,"button");
button.setTag(projectName );
USE
function buttonActiveProjectsChartHandler_1(button){
...
buttonTag = getButtonTag(button);
chartType = buttonTag.split(";")[1];
activeProject = buttonTag.split(";")[0];
...
}
function getButtonTag(button){
var jsonButton = JSON.stringify(button);
var source = button.parameter.source;
var tagPtr = source + "_tag";
return button.parameter[tagPtr];
}

Do something on :target with javascript

I'm using the CSS3 :target pseudo selector to create in-page navigation without reloading the page. This works really well!
But I have a problem, I need to reset the forms in a page when the page targetted, how can I know if an element is targetted with javascript? Like element.ontarget = function();
Or maybe something like element.ondisplaychange -> element.oncsschange?
BETTER UPDATE:
var hashcache = document.location.hash;
window.onhashchange = function() {
if(hashcache != document.location.hash) {
$(hashcache + ' form input').each(function() {
$(this).val('');
});
hashcache = document.location.hash;
}
}
UPDATE:
$('a[href^="#"]').each(function() {
this.onclick = function() {
href = $(this).attr('href');
if(href != document.location.hash) {
$(href + ' form input').each(function() {
$(this).val('');
});
}
}
});

If you're using JavaScript for the navigation, I'd suggest just adding the check to that. But I'm guessing from your question you're not, that you're instead using plain links with just anchors (e.g., <a href='#target1'>, <a href='#target2'>, ...).
A couple of options:
Use a Timer
In that case, basically what you want to do boils down to receiving an event when the anchor changes. As far as I know, and as far as the people answering this other question on StackOverflow in January knew, you can only do that with a timer. (Edit: But see ide's comment below, there's a new hashchange event we'll be able to use soon!) E.g.:
(function() {
var lastHash = window.location.hash;
setTimeout(function() {
var newHash = window.location.hash;
if (newHash !== lastHash) {
lastHash = newHash;
// Trigger your target change stuff
}
}, 250);
})();
That checks for changes every quarter second. That may not be enough for you, you could lower the 250, but beware running too much and slowing everything else down.
But as you say below, this is inefficient.
Hook the Link's click event
Since you're already using JavaScript on the page, I'd recommend using handlers on your links instead. If you add a class name or something to them (I bet they already have one; I'll us "navlink" below), this is easily set up:
var links, index, link;
links = document.getElementsByTagName('a');
for (index = 0; index < links.length; ++index) {
link = links.item(index);
if ((" " + link.className + " ").indexOf(" navlink ") >= 0) {
hookEvent(link, 'click', clickHandler);
}
}
function clickHandler() {
// `this` will reference the element that was clicked
}
// The 'hook' function:
var hookEvent = (function() {
var elm = document.createElement('a');
function hookEventViaAttach(element, event, handler) {
element.attachEvent("on" + event, handler);
}
function hookEventViaAddListener(element, event, handler) {
element.addEventListener(event, handler, false);
}
function hookEventDOM0(element, event, handler) {
element["on" + event.toLowerCase()] = handler;
}
if (elm.attachEvent) {
return hookEventViaAttach;
}
if (elm.addEventListener) {
return hookEventViaAddListener;
}
// I usually throw a failure here saying not supported, but if you want,
// you can use the DOM0-style stuff.
return hookEventDOM0;
})();
A lot of the complication of the above goes away if you use a library like jQuery, Prototype, YUI, Closure, or any of several others.
For instance, the jQuery version:
$("a.navlink").click(clickHandler);
function clickHandler() {
// `this` will reference the element that was clicked
}
The Prototype version:
$$("a.navlink").invoke('observe', 'click', clickHandler);
function clickHandler() {
// `this` will reference the element that was clicked
}

The onfocus property returns the onFocus event handler code on the current element.
event handling code = element.onfocus
The onblur property returns the onBlur event handler code, if any, that exists on the current element.
element.onblur = function;
Example: http://jsfiddle.net/g105b/cGHF7/
<html>
<head>
<title>onblur event example</title>
<script type="text/javascript">
var elem = null;
function initElement()
{
elem = document.getElementById("foo");
// NOTE: doEvent(); or doEvent(param); will NOT work here.
// Must be a reference to a function name, not a function call.
elem.onblur = doEvent;
};
function doEvent()
{
elem.value = 'Bye-Bye';
alert("onblur Event detected!")
}
</script>
<style type="text/css">
<!--
#foo {
border: solid blue 2px;
}
-->
</style>
</head>
<body onload="initElement()";>
<form>
<input type="text" id="foo" value="Hello!" />
</form>
<p>Click on the above element to give it focus, then click outside the
element.<br /> Reload the page from the NavBar.</p>
</body>
</html>

Maybe youcan just code like this
function hashChangeEvent(){
$(window.location.hash)//do something
}
window.onhashchange = hashChangeEvent;//when hash change
hashChangeEvent();//first load