I'm working on a website where I want to show and hide images by clicking on a button/word. I used bit of code and it's working:
function myFunction() {
var x = document.getElementById("myDIV");
if (x.style.display === "none") {
x.style.display = "block";
} else {
x.style.display = "none";
}
}
Similar to the one used in a previous stack overflow question on this topic:
var button = document.getElementById('button'); // Assumes element with id='button'
button.onclick = function() {
var div = document.getElementById('newpost');
if (div.style.display !== 'none') {
div.style.display = 'none';
}
else {
div.style.display = 'block';
}
};
However, I want the image to be hidden when you enter or refresh the site instead of shown. So instead of it starting by showing the image and hiding it when you click on the word, I want it to be hidden and shown when you click the word. How do I change the script to make that happen?
I tried to switching the "none" and "block" but it didn't work haha...
Thanks
You can hide the image when the script runs, which is when the page is loaded or refreshed.
So just adding one line is enough.
const button = document.getElementById("button") // Assumes element with id='button'
const imageElement = document.getElementById("newpost")
// Hide the image at the start
imageElement.style.display = "none"
// Toggle it on click
button.addEventListener('click', () => {
imageElement.style.display =
imageElement.style.display === "none" ? "block" : "none"
})
I also modified your code to make it a bit easier to read by using a ternary operator.
And in case you are using the .onClick method from the example: Prefer using addEventListener over .onX methods. More about that on MDN and on this answer.
Related
I'm fairly new in with JS and was wondering, if
there is a more cleaner way of writing this code?
I'm trying to create a button that shows or hides a div depending on whether it is currently showing.
Many Thanks in Advance
Anne
var button = document.getElementById('button');
var hideText = document.getElementById('output').className = 'hide';
button.addEventListener('click', ()=>{
if(hideText){
document.getElementById('output').className = 'unhide';
hideText = false;
}else{
document.getElementById('output').className = 'hide';
hideText = true;
}
})
CSS
.hide{display: none;}
.unhide{display: block;}
Just use a single class (e.g. unhide) and make it invisible by default. Then do
button.addEventListener('click', () => {
document.getElementById('output').classList.toggle('unhide');
}
You can just toggle the classes
button.addEventListener('click', () => {
document.getElementById('output').classList.toggle('hide');
}
You can remove the extra variable hideText and also the extra css if you implement like this
var x = document.getElementById("output");
if (x.style.display === "none") {
x.style.display = "block";
} else {
x.style.display = "none";
}
In jquery the are other simpler possible way like toggle, hide, show.
The purpose of the code is to hide/show an element when the header element is clicked. Why code works and doesn't isn't clear.
Example 1
function showHideAnswers (id) {
var x = document.getElementById(id);
if (x.style.display === "") {
x.style.display = "block";
}
}
The above code works. Notice the display if comparision of "" rather than none.
Example 2
function showHideAnswers(id) {
var x = document.getElementById(id);
if (x.style.display === "none") {
x.style.display = 'block';
}
}
This code does not work. Notice display being compared to "none", which I think is the part that is causing it to fail; however, "none" works in example 3.
Example 3
function showHideAnswers(id) {
var x = document.getElementById(id);
if (x.style.display === "none") {
x.style.display = 'block';
} else {
x.style.display = 'none';
}
}
This code works, which causes me to be confused as to why example 2 doesn't work.
element.style will return the value only inline style is present otherwise "" will be returned
Use Window.getComputedStyle instead!
function showHideAnswers(id) {
var x = document.getElementById(id);
var style = window.getComputedStyle(x, null);
if (style.display === "none") {
x.style.display = 'block';
} else {
x.style.display = 'none';
}
}
<div id='elem'>Element</div>
<button onclick="showHideAnswers('elem')">Click me!</button>
in the second example you are asking if x.style.display is equal to the string "none". the default value of display is inline so its checking if "inline" === "none". To fix the problem you must put the x.style.display to "none" before you run this code
In example 1, it will not work if display is already set to anything. (This will only show if display is unset, no hiding).
In example 2, you will only get action if display is explicitly set to none already. (This will only show if the element isn't already hidden, no hiding)
In example 3 you have an else clause which covers the opposite case, and so it will work for both cases (show and hide). Another reason that 3 works is because if display is unset, then the else clause will cause it to be set to none, and then block and vice-versa as you continue to call the function.
Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 6 years ago.
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I am really new to JS and I'm having some issues.
So I have this JS file: that is basically the same function repeating with different <div id="">.
var button = document.getElementById("obj-trigger");
button.onclick = function () {
var div = document.getElementById("obj-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("lineas-trigger");
button.onclick = function() {
var div = document.getElementById("lineas-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("cultura-trigger");
button.onclick = function() {
var div = document.getElementById("cultura-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("igualdad-trigger");
button.onclick = function() {
var div = document.getElementById("igualdad-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("proyectos-trigger");
button.onclick = function() {
var div = document.getElementById("proyectos-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("estigmas-trigger");
button.onclick = function() {
var div = document.getElementById("estigmas-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("soy-trigger");
button.onclick = function() {
var div = document.getElementById("soy-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
var button = document.getElementById("tudef-trigger");
button.onclick = function() {
var div = document.getElementById("tudef-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
And it works perfectly when I am using ALL the functions, however if I remove a <div> from my HTML, let's say: <div id="estigmas-trigger">, my JS will work until it reaches:
var button = document.getElementById("estigmas-trigger");
button.onclick = function() {
var div = document.getElementById("estigmas-cont");
if (div.style.display !== "none") {
div.style.display = "none"
}
else {
div.style.display = "block";
}
};
All code below that will stop working, so no more collapsing. :(
Why is that? And... how can I fix it?
It's because button will be null if there are no element with id estigmas-trigger, and you should get error that you can't set value onclick on null, try adding a check to test if button is not null:
var button = document.getElementById("estigmas-trigger");
if (button) {
button.onclick = function() {
var div = document.getElementById("estigmas-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
}
Your error is caused because when you remove an element from the HTML and then your Javascript tries to refer to that element without proper protections, it causes a script error and the script aborts execution because of the error.
The second thing you need to do when learning Javascript (after learning how to write your first script) is to learn how to check for errors in the debug console in the browser. That will show you when you have execution errors that are aborting your script and they will usually show you what line the error occurs on.
In this case, you would attempt to get a DOM element with a line such as:
var button = document.getElementById("estigmas-trigger");
And, then you would attempt to use the button variable. But, if the estigmas-trigger element was not in the page, then button would be null and it would be an error to reference a property of null such as .onclick.
In addition, your code is horribly repetitive. You really should never copy nearly identical code multiple times into your code. Instead, create a reusable function and use that function multiple places or if your code is almost entirely identical except for one input parameter (which is the case for you), then you can just put the one input parameter into an array and loop through the array.
Here's a much more DRY implementation (this replaces all of your code):
var buttons = ["obj-trigger", "lineas-trigger", "cultura-trigger",
"igualdad-trigger", "proyectos-trigger", "estigmas-trigger",
"soy-trigger", "tudef-trigger"];
buttons.forEach(function(id) {
var button = document.getElementById(id);
if (button) {
button.addEventListener("click", function(e) {
var cont_id = this.id.replace("trigger", "cont");
var elem = document.getElementById(cont_id);
if (elem) {
var style = elem.style;
if (style.display !== "none") {
style.display = "none";
} else {
style.display = "block";
}
}
});
}
});
Summary of changes:
Put all the trigger ID values into an array of strings so you can just loop through each one that you want to apply identical code to.
Use .forEach() to loop through the array of strings.
Get the DOM element for each id and check to see if it is present before trying to use it (this will solve your original problem).
Use .addEventListener() to add the click event handler as this is much more scalable than .onclick because you can have multiple click handlers for the same element this way. It is a generally good habit to switch to use .addEventListener().
Rather than refer to the xxx-cont ids by name, just derive them from the xxx-trigger ids using a simple text replacement. This saves more duplication and typing in your code.
Get the xxx-cont object in the DOM and also check to see if it exists before attempting to use it (safe coding).
One way is:
var button = document.getElementById("estigmas-trigger");
//that way you prevent define a function in a null object
if(button){
button.onclick = function() {
var div = document.getElementById("estigmas-cont");
if (div.style.display !== "none") {
div.style.display = "none";
}
else {
div.style.display = "block";
}
};
}
I have a small bit of javascript for showing and hiding a div.
function hidefooter(){
var button = document.getElementById('footerbutton');
button.onclick = function() {
var div = document.getElementById('footerbox');
if (div.style.display !== 'block') {
div.style.display = 'block';
}
else {
div.style.display = 'none';
}
};
}
The div starts {display:none;}. I looked around online and could only find people saying it was an html thing. My problem with that was that when i first wrote it the "block" and "none" values were switched and it took 3 clicks to work. Any help would be great.
update: A better explanation. This code does exactly what i want but you have to click twice to get the effect to work. At first i had the "block" and "none" properties switched and it took 3 clicks to get it to work. The footer starts out {display:none;}. I put it up online so a friend could take a look at it. the url is http://www.miettegoesplaces.com. click on the purple foot button on the right.
update 2: sorted the problem was i was calling the onClick twice. this is the simplified working version.
function hideFooter(){
var div = document.getElementById('footerbox');
if (div.style.display !== 'block') {
div.style.display = 'block';
}
else {
div.style.display = 'none';
}
};
thanks for everyones comments and advice.
You have added click event twice here.
First, you are calling onClick event on button.
Inside hidefooter() function, you have defined button.onclick = function() {...}
remove button.onclick = function() {} and use like this :
function hidefooter(){
var button = document.getElementById('footerbutton');
var div = document.getElementById('footerbox');
if (div.style.display != 'block') {
div.style.display = 'block';
}
else {
div.style.display = 'none';
}
Here is the working fiddle.
you need to add "display: none" to your footer's style
You can use window.getComputedStyle(elem) for Firefox, Opera, Safari and Chrome or elem.currentStyle for IE
var button = document.getElementById('footerbutton');
button.onclick = function() {
var div = document.getElementById('footerbox');
var style = window.getComputedStyle(div);
if (style.display !== 'block') {
div.style.display = 'block';
}
else {
div.style.display = 'none';
}
};
Just remove the code that you use to define a button that handles events and add an onClick() event to your button instead
This code will work as you want it
function hidefooter(){
var div = document.getElementById('footerbox');
if (div.style.display !== 'block') {
div.style.display = 'block';
}
else {
div.style.display = 'none';
}
}
But make sure your button code looks like this:
<button id="footerbutton" onClick="hidefooter()">Hide Footer</button>
Pay attention to onClick="hidefooter()"
And make sure your div is still display:none;
I believe the problem was that you're using the 'hide' button to define what it does and THEN do the hiding work. You should add an event handler that calls the hidefooter() function instead which has nothing but the footer hiding code.
This is my script :
window.onload = function (){
var title = document.getElementsByTagName('h1')[0].id = "heading1";
document.getElementById(title).onclick = function (e){
var para = this.nextSibling.style.display = 'block';
var newVal = (para == "block") ? "none" : "block";
alert(newVal);
}
}
The result I need is for the alert value to toggle from block to none and back. But I am always getting "none". What is the problem with my code?
window.onload = function () {
var firstH1 = document.getElementsByTagName('h1')[0];
firstH1.id = "heading1";
firstH1.onclick = function() {
var currentValue = this.nextSibling.style.display;
this.nextSibling.style.display = (currentValue == "none") ? "block" : "none";
}
}
Note a few things: I simplified your element fetching because it doesn't make sense to fetch an element, assign it an id, then use that id to find that same element again.
I also switched block/none ordering, because if no style is displayed then it would be blank -- and your first click would assign block to it - and it would not disappear. This way it does.
Well, para will always be "block", and therefore newVal will always be "none". So that behavior is expected. What are you trying to do? you are not toggling the property with your curent code.