Develop Reference

addEventListener for the same event

So I have a few div tags that I have currently hidden, and I want to display them one after the other by hitting the enter key.
What I want to happen: I hit enter and the first div tag is revealed, and then I hit enter a second time to see the second div tag.
What is happening instead: I hit enter once and both div tags show up.
In this case, the first div tag I want to reveal is "intro", and the second is "body". I am running this website on jsbin, and I am using chrome, if that helps.
This is my JavaScript:
//***********************************************************
// BODY MODULE
var bodyController = (function(){
var enterBool;
var reveal = function(){
if(enterBool){
document.getElementById("evidence").style.display = "block";
enterBool = false;
}
};
var enterListen = function(){
document.addEventListener("keydown", function(event){
if(event.keyCode === 13){
document.addEventListener("keyup", function(event){
if(event.keyCode === 13){
enterBool = true;
reveal();
}
});
}
});
};
return{
enterBoolBody: enterBool,
enterListenBody: function(){
enterListen();
}
}
})();
//***********************************************************
// INTRO MODULE
var introController = (function(){
var enterBool;
var reveal = function(){
if(enterBool){
document.getElementById("body").style.display = "block";
enterBool = false;
}
};
var enterListen = function(){
document.addEventListener("keydown", function(event){
if(event.keyCode === 13){
document.addEventListener("keyup", function(event){
if(event.keyCode === 13){
enterBool = true;
reveal();
}
});
}
});
};
return{
enterBoolIntro: enterBool,
enterListenIntro: function(){
enterListen();
}
}
})();
//***********************************************************
// CONTROL MODULE
var controller = (function(introCtrl, bodyCtrl, evidenceCtrl, infoCtrl,
conclusionCtrl){
var eventListeners = function(){
introCtrl.enterListenIntro();
bodyCtrl.enterListenBody();
};
return{
init: function(){
eventListeners();
}
}
})(introController, bodyController, evidenceController,
infoController, conclusionController);
//***********************************************************
controller.init();

I think you might be over engineering this a bit. All you need is an event listener to check for enter. Then you check if the first div is shown, if not show it. If the first div is shown check if the second div is shown and show it.
Quick note, no IE9 support for classList if that's important to you.
https://caniuse.com/#feat=classlist
(function(window, document, undefined)
{
document.addEventListener('keyup', showDivs, false);
})(window, window.document);
function showDivs(event)
{
event = event || window.event;
var divsToShow = document.getElementsByClassName("Display-Div");
for (var i = 0; i < divsToShow.length; i++) {
if (!divsToShow[i].classList.contains("Block")) {
divsToShow[i].classList.add("Block");
break;
}
}
}
.Hidden {
display: none;
}
.Block {
display: block;
}
<div class="Hidden Display-Div">This</div>
<div class="Hidden Display-Div">Now</div>
<div class="Hidden Display-Div">Works</div>
<div class="Hidden Display-Div">With</div>
<div class="Hidden Display-Div">Any</div>
<div class="Hidden Display-Div">Div</div>
<div class="Hidden Display-Div">With</div>
<div class="Hidden Display-Div">Class</div>
<div class="Hidden Display-Div">Display-Div</div>

You can put the ids of your divs in an array, or you could assign a common class to all divs that you want to appear one by one. Assuming the first, this code simply grabs the id of the next div to display from the array and increments the counter. You could add more divs to the array and it would work.
var divs = ["evidence", "body"];
var counter = 0;
document.addEventListener("keyup", function(event){
if(counter < divs.length && event.keyCode == 13){
document.getElementById(divs[counter]).style.display = 'block';
counter++;
}
});

Function activate after two onclicks

Hey I'm using javascript+html only.
Is there any way to activate a function after the button has been clicked two (or more) times? I want the button to do NOTHING at the first click.

For a "doubleclick", when the user quickly presses the mouse button twice (such as opening a program on the desktop), you can use the event listener dblclick in place of the click event.
https://developer.mozilla.org/en-US/docs/Web/Reference/Events/dblclick
For a quick example, have a look at the below code. http://jsfiddle.net/jzQa9/
This code just creates an event listener for the HTMLElement of "item", which is found by using getElementById.
<div id="item" style="width:15px;height:15px;background-color:black;"></div>
<script>
var item = document.getElementById('item');
item.addEventListener('dblclick',function(e) {
var target = e.target || e.srcElement;
target.style.backgroundColor = 'red';
},false);
</script>
As for wanting the user to click an element X times for it to finally perform an action, you can do the following. http://jsfiddle.net/5xbPG/
This below code works by adding a click tracker to the HTMLElement and incrementing the click count every time it's clicked. I opted to save the clicks to the HTMLElement instead of a variable, but either way is fine.
<div id="item" style="width:15px;height:15px;background-color:black;"></div>
<script>
var item = document.getElementById('item');
item.addEventListener('click',function(e) {
var target = e.target || e.srcElement;
var clicks = 0;
if(target.clicks)
clicks = target.clicks;
else
target.clicks = 0;
if(clicks >= 4) {
target.style.backgroundColor = 'red';
}
target.clicks += 1;
},false);
</script>
== UPDATE ==
Since you recently posted a comment that you want two different buttons to be clicked for an action to happen, you would want to do something like this... http://jsfiddle.net/9GJez/
The way this code works is by setting two variables (or more) to track if an element has been clicked. We change these variables when that item has been clicked. For each event listener at the end of changing the boolean values of the click state, we run the function checkClick which will make sure all buttons were clicked. If they were clicked, we then run our code. This code could be cleaned up and made to be more portable and expandable, but this should hopefully get you started.
<input type="button" id="button1">
<input type="button" id="button2">
<div id="result" style="width:15px;height:15px;background-color:black;"></div>
<script>
var result = document.getElementById('result');
var button1 = document.getElementById('button1');
var button2 = document.getElementById('button2');
var button1Clicked = false;
var button2Clicked = false;
button1.addEventListener('click',function(e) {
button1Clicked = true;
checkClick();
},false);
button2.addEventListener('click',function(e) {
button2Clicked = true;
checkClick();
},false);
function checkClick() {
if(button1Clicked && button2Clicked) {
result.style.backgroundColor = 'red';
}
}
</script>

Two ways you can do this, one would be to have a data attribute within the html button that identifies whether the click has been done.
<button id="btn">Click Me!</button>
<script>
var clickedAlready = false;
document.getElementById('btn').onclick = function() {
if (clickedAlready) {
//do something...
}
else
clickedAlready = true;
}
</script>
While global variables aren't the best way to handle it, this gives you an idea. Another option would be to store the value in a hidden input, and modify that value to identify if it's the first click or not.

Maybe something like this?
var numberTimesClicked = 0;
function clickHandler() {
if (numberTimesClicked > 0) {
// do something...
}
numberTimesClicked++;
}
document.getElementById("myBtn").addEventListener("click", clickHandler);

Show button if input is not empty

I am not much of a JavaScript guru, so I would need help with a simple code.
I have a button that clears the value of an input field.
I would like it (the button) to be hidden if input field is empty and vice versa (visible if there is text inside the input field).
The solution can be pure JavaScript or jQuery, it doesn't matter. The simpler, the better.

$("input").keyup(function () {
if ($(this).val()) {
$("button").show();
}
else {
$("button").hide();
}
});
$("button").click(function () {
$("input").val('');
$(this).hide();
});
http://jsfiddle.net/SVxbW/

if(!$('input').val()){
$('#button').hide();
}
else {
$('#button').show();
}
In it's simplest form ;)

to do this without jQuery (essentially the same thing others already did, just pure js). It's pretty simple, but I've also added a few comments.
<body>
<input type="text" id="YourTextBox" value="" />
<input type="button" id="YourButton" value="Click Me" />
<script type="text/javascript">
var textBox = null;
var button = null;
var textBox_Change = function(e) {
// just calls the function that sets the visibility
button_SetVisibility();
};
var button_SetVisibility = function() {
// simply check if the visibility is set to 'visible' AND textbox hasn't been filled
// if it's already visibile and the text is blank, hide it
if((button.style.visibility === 'visible') && (textBox.value === '')) {
button.style.visibility = 'hidden';
} else {
// show it otherwise
button.style.visibility = 'visible';
}
};
var button_Click = function(e) {
// absolutely not required, just to add more to the sample
// this will set the textbox to empty and call the function that sets the visibility
textBox.value = '';
button_SetVisibility();
};
// wrap the calls inside anonymous function
(function() {
// define the references for the textbox and button here
textBox = document.getElementById("YourTextBox");
button = document.getElementById("YourButton");
// some browsers start it off with empty, so we force it to be visible, that's why I'll be using only chrome for now on...
if('' === button.style.visibility) { button.style.visibility = 'visible'; }
// assign the event handlers for the change and click event
textBox.onchange = textBox_Change;
button.onclick = button_Click;
// initialize calling the function to set the button visibility
button_SetVisibility();
})();
</script>
</body>​
Note: I've written and tested this in IE9 and Chrome, make sure you test it in other browsers. Also, I've added this fiddle so you can see it working.

You can use $('selector').hide() to hide an element from view and $('selector').show() to display it again.
Even better, you can use $('selector').toggle() to have it show and hide without any custom logic.

First hide the button on page load:
jQuery(document).ready(function() {
jQuery("#myButton").hide();
});
Then attach an onChange handler, which will hide the button whenever the contents of the text-field are empty. Otherwise, it shows the button:
jQuery("#myText").change(function() {
if(this.value.replace(/\s/g, "") === "") {
jQuery("#myButton").hide();
} else {
jQuery("#myButton").show();
}
});
You will also need to hide the button after clearing the input:
jQuery("#myButton").click(function() {
jQuery("#myInput").val("");
jQuery(this).hide();
});

Preventing mouse click event from firing on elements on a particular z-index

Is there any way to disable onclick events from firing for events on a particular z-index, besides running through all elements and setting their onclick to function(){} if they are on that z-index?
Edit:
At this point, the best I can come up with is to hook each function in the DOM tree recursively:
function preventZIndexClicks(elem) {
// ensure not a text node
if(!elem.popupflag) { elem.popupflag = 1;
if(elem.onclick) { var temp = elem.onclick;
elem.onclick = function(e) {
if(g_threshold > elem.style.zIndex)
return;
temp(e);}
}
}
// Call recusively on elem.childNodes
}
Of course, then I would have to deal with the rather annoying IE issues with setting custom properties on DOM elements...

You could check the z-index in the event and let it bubble through the rest.
function onclick(e) {
if(this.style.zIndex == 10) return;
//do stuff
}
EDIT:
Just to clarify how i mean, consider this:
<div id="div1" style="background-color: red;width:100px;height:100px;z-index:1">
<div id="div2" style="background-color: green;width:50px;height:50px;z-index:2">
<div id="div3" style="background-color: blue;width:25px;height:25px;z-index:3">
</div>
</div>
</div>
With this javascript:
var div1 = document.getElementById("div1");
var div2 = document.getElementById("div2");
var div3 = document.getElementById("div3");
bind(div1,"click",click);
bind(div2,"click",click);
bind(div3,"click",click);
function click(e) {
if(this.style.zIndex == 2) return;
alert(this.style.backgroundColor);
}
function bind(element,event,callback){
var onevent="on"+event;
if(element.addEventListener)
element.addEventListener(event,callback,false);
else if(element.attachEvent)
element.attachEvent(onevent,callback);
else{
var e=element[onevent];
element[onevent]=function(){
var h=e.apply(this,arguments),cbk=callback.apply(this,arguments);
return h==undefined?cbk:(cbk==undefined?h:cbk&&h);
}
}
}
Now, the click will work as follow:
click red: -> alert "red"
click green: -> alert "red"
click blue: -> alert "blue" -> alert "red"
As you see the green element with z-index:2; will not "fire" the event

What about something like:
<script type="text/javascript">
window.onclick = function(e)
{
var targetElem;
if (!e)
{
var e = window.event;
}
if (e.target)
{
targetElem = e.target;
}
else if (e.srcElement)
{
targetElem = e.srcElement;
}
if (targetElem.nodeType == document.TEXT_NODE)
{
targetElem = targetElem.parentNode;
}
if (targetElem.style.zIndex == 100)
{
// do stuff
}
};
</script>

with jQuery:
$('*').each(function() {
var $this = $(this);
if ($this.css('z-index') < g_threshold) {
$this.unbind('click'); //unbinds all click handlers from a DOM element
$this.click(function(e) {
e.stopPropagation();
});
}
});
this is basically like what you do, but requires no additional attributes or whatever else you dislike. If you need to leave, say, textbox untouched, then use $('*').not('input:text')

I am trying to make a simple toggle button in javascript

I am trying to make a simple toggle button in javascript. However, the button will only turn "OFF" and will not turn back "ON"
<html><head></head>
<script type="text/javascript">
function toggle(button)
{
if(document.getElementById("1").value=="OFF"){
document.getElementById("1").value="ON";}
if(document.getElementById("1").value=="ON"){
document.getElementById("1").value="OFF";}
}
</script>
<body>
<form action="">
<input type="button" id="1" value="ON" style="color:blue"
onclick="toggle(this);">
</form></body></html>
I am running:HP Netbook : Ubuntu Linux 10.04 : Firefox for Ubuntu 1.0.

Why are you passing the button if you're going to look it up?
Also, since you know the possible values, you only need to check if it's OFF, otherwise, you know it's ON.
// Toggles the passed button from OFF to ON and vice-versa.
function toggle(button) {
if (button.value == "OFF") {
button.value = "ON";
} else {
button.value = "OFF";
}
}
If you wanna get fancy and save a couple of bytes you can use the ternary operator:
function toggle(b){b.value=(b.value=="ON")?"OFF":"ON";}

Both of your if statements are getting executed one after each other, as you change the value and then immediately read it again and change it back:
function toggle(button)
{
if(document.getElementById("1").value=="OFF"){
document.getElementById("1").value="ON";}
else if(document.getElementById("1").value=="ON"){
document.getElementById("1").value="OFF";}
}
Adding the else in there should stop this happening.

Another method to do this is:
var button = document.querySelector("button");
var body = document.querySelector("body");
var isOrange = true;
button.addEventListener("click", function() {
if(isOrange) {
body.style.background = "orange";
}else {
body.style.background = "none";
}
isOrange = !isOrange;
});
In the JavaScript file.
/*****
NOTE!
Another way is applying a class to the element that we want to change.
The CSS file must have the class with the format we want:
.orange {
background: orange;
}
By last in our js file we only need to make the application of the class:
var button = document.querySelector("button");
button.addEventListener("click", function() {
document.body.classList.toggle("orange");
});
Regards :)

Why not use a switch?
function toggle(button)
{
switch(button.value)
{
case "ON":
button.value = "OFF";
break;
case "OFF":
button.value = "ON";
break;
}
}

<html>
<head>
<script type="text/javascript">
function toggle(button)
{
if(document.getElementById("1").value=="OFF")
{
document.getElementById("1").value="ON";
}
else
{
document.getElementById("1").value="OFF";
}
}
</script>
</head>
<body>
<form action="">
<input type="button" id="1" value="ON" style="color:blue" onclick="toggle(this);">
</form>
</body>
</html>

This will resolve your issue.
let isOn = true;
function toggle(button) {
isOn = !isOn;
if (isOn) {
document.getElementById("1").value = "ON";
} else {
document.getElementById("1").value = "OFF";
}
}