Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 2 years ago.
Improve this question
I have a lot of questions its all on java script (with some jquery)
first im trying to detect the mouse X cordinates when the mousemove on an element :
(function() {
'use strict';
$('.AnyElement').mousemove(function (e) {
console.log(e.pageX)
});
})();
i want to detect the mouse X once i know theres a functions like mouseover etc...
but in general how to make this function run once and stop
Second when someone write :
if (document.body = 1) {
// do anything
}
he is checking if document.body equal to 1
i see a thing in someone else code i dont undertand here it is :
if (document.body) {
// do anything
}
it doesnt matter what the function do , the thing is what he is checking ???
In answer to your first question there are a few ways you could do it, one example would be to register the mousemove event and then remove the event after logging it once.
$('html').mousemove(function(e) {
console.log(e.pageX);
$('html').off('mousemove');
})
Another method could be use the one event listener built into jQuery.
$('html').one('mousemove',function(e) {
console.log(e.pageX);
});
In answer to your second question the first statement is looking for the length of the element, if the element exists it will generally be greater than 0. In the second statement document.body will return a boolean of true or false depending on whether or not the element exists. Again there are a million different ways you can do the same thing in Javascript.
Hope that helps!
Related
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 4 months ago.
Improve this question
Does anyone have any idea how to stop an interval that is situated inside of a function once it's done doing its thing?
Here is what I mean:
function renderMessage(message) {
const renderInterval = setInterval(() => {
characterIndex++;
dealerMessage.innerHTML = `
${messages[message].slice(0, characterIndex)}
`;
if (characterIndex === messages[message].length) {
clearInterval(renderInterval)
}
}, 100);
}
As you can see, I'm trying to render out a message using this function. It does its job fine, but if I don't stop it, subsequent messages keep overriding themselves...
I've tested the if check and it is actually functioning inside the function, yet for some reason the clearInterval doesn't work.
Is there any way I can fix this, or do you recommend me to start from scratch?
Note: this method would be very handy for me, so, if possible, I would like to keep it.
I think your 'if' statement of clearInterval should be
if (characterIndex===message[message.length]){}
Also, I cannot see any initialization of the characterIndex variable. Please do inform if this worked or not.
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 2 years ago.
Improve this question
Does anyone know how does this if statement "escape 2 functions at the same time"
client.on('message', message => {
if (Math.floor(Math.random()*20) === 19) return;
//rest of code
}
Like it escapes its if check and the .on message event.
Also, this is probably a dupe, but I couldn't find what I was looking for or didn't know what to search for.
Just to add, an analogy would be like when you use break; + labels: to stop a loop from going on. See, if I used a return; it would only stop the if statement (in the below code ofc), and the for loop would continue. But if I used a break start; it would also stop the for loop, this is what am trying to do.
start: {
for (var i = 0; i > x; i++) {
if (x === 1) {
break start;
}
//code
}
}
You can't escape the if condition. If you want this to do nothing, then simply return.
client.on('message', message => { return; })
// or, more concisely
client.on('message', () => {})
But this is a strange thing to do, unless you were trying to override the on callback method. But I assume is an event emitter that can have multiple subscribers, so that doesn't make sense either.
I guess what you want do is to detach your listener from emitter on certain condition. You would have to change your calls a little: add a function name and you will be able to adress it its body. Then you just detach your listener when your condition is met:
client.addListener('message', function onMessage(message) {
if (Math.floor(Math.random()*20) === 19) {
client.removeListener('message', onMessage);
}
}
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 3 years ago.
Improve this question
I would like you to tell me if there is an event that returns to me when it was the last time a user touched the screen, since I need a function to run 3 seconds after the user touched the screen for the last time
There's no specific event for your use-case. What you can do however is adding a click event listener to your window object and assign the current time to a global variable as soon as someone clicked the screen. Additionally you have to use JavaScript's setInterval() method, which executes a function periodically e.g. every 20 ms. Inside it's callback function you can compare the current time to the time stored in the global variable and if the difference is bigger than 3000 trigger your action.
Here's an example (just click 'Run code snippet'):
var timeClicked;
function screenClicked() {
timeClicked = new Date();
}
function check() {
if (timeClicked != null) {
if (new Date() - timeClicked > 3000) {
clearInterval(interval);
alert("time's up!");
}
}
}
window.addEventListener("click", screenClicked);
var interval = setInterval(check, 20);
<body bgcolor="#eeeeee"><span>click anywhere inside this window</span></body>
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 7 years ago.
Improve this question
I'm wondering how can I rewrite this javascript function into jQuery but using if/else statements instead of while:
<textarea style="overflow-y: hidden;" onkeyup="expandtext(this);"></textarea>
function expandtext(textArea){
while (textArea.rows > 1 && textArea.scrollHeight < textArea.offsetHeight) {
textArea.rows--;
}
while (textArea.scrollHeight > textArea.offsetHeight) {
textArea.rows++;
}
textArea.rows++
}
Well, since you appear to want it so badly, here it is
$.fn.expandText = function () {
$.each(this, function (k, textArea) {
while (textArea.rows > 1 && textArea.scrollHeight < textArea.offsetHeight) {
textArea.rows--;
}
while (textArea.scrollHeight > textArea.offsetHeight) {
textArea.rows++;
}
textArea.rows++
});
}
$('textarea').expandText();
FIDDLE
Additionally, I think I understand what you wanted to ask. In order to understand this you need a good understanding of javascript objects and document object model. There are special properties of objects in the DOM which affect how the objects are displayed (this is all done by your browser automatically), rows is one of those properties, and in order for the element on the page to change in height, which is the goal of this function, you need to change the property rows on the specific element. You can't do this with jQuery (or maybe you can, who knows) because it wraps your object in other objects. Even if it is possible, you are going to have to call a function on the wrapper object which is then going to access the DOM object and change it's property, which is what your function does in the first place, so why bother at all.
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
If I write this:
$('#SomeDiv').click(DoSomething);
function DoSomething() {
if (SomeCondition === true) {
return false;
}
// more code here
}
regardless of whether I put return; or return false; or return true; the code doesn't throw exceptions and the function execution stops.
Which is the best option?
If those are the only options, use return; in this case. (read below)
If the function normally returns something (calculates something, gets some value, etc) then you definitely don't want to return anything, because you might confuse the caller.
If your function doesn't normally return anything, then it might not hurt to return anything you like, but it might still confuse callers.
I would personally rather just put an else after the if, and not use the return;. And if the function gets too large, just retractor it a bit.
If you just want to stop the function on some condition and don't care what it returns, then it doesn't matter which of the three you choose. If you're not using the output of the function, I'd just use a simple return; statement to stop it executing further.