Javascript: automatize function [duplicate] - javascript

This question already has answers here:
JavaScript closure inside loops – simple practical example
(44 answers)
Closed 6 years ago.
Good day,
I have a piece of code that is aimed to perform action on mouse click. First I have made a function that scrolls screen on element when I perform a click on another element:
(function($) {
$.fn.goTo = function() {
$('html, body').animate({
scrollTop: $(this).offset().top + 'px'
}, 'fast');
}
})(jQuery);
than I assign this function to specific DOM elements:
$('#collapse1').on('shown.bs.collapse', function () {
$('#s1').goTo();
});
$('#collapse2').on('shown.bs.collapse', function () {
$('#s2').goTo();
});
$('#collapse3').on('shown.bs.collapse', function () {
$('#s3').goTo();
});
$('#collapse4').on('shown.bs.collapse', function () {
$('#s4').goTo();
});
etc...
"shown.bs.collapse" is actually from bootstrap collapse.js.
"This event is fired when a collapse element has been made visible to the user (will wait for CSS transitions to complete)."
The code is working but it is really not looks good. Is there the way to make some sort of cycle? Standard "for" is not working:
var collapseNumber = jQuery.makeArray(document.getElementsByClassName("panel panel-default"));
for (var i = 0; i < collapseNumber.length; i++) {
$('#collapse' + i).on('shown.bs.collapse', function () {
$('#s' + i).goTo();
});
}
created array is for getting actual number of elements, which I need to put in the cycle.

The problem you have is the infamous for loop issue where the value of i is the last value. But there is no reason to have to loop when a simple data attribute can be used.
Just use a data-attribute to select and link the things
<div data-goto="#s1">...</div>
and the JavaScript
$('[data-goto]').on('shown.bs.collapse', function () {
var selector = $(this).data("goto");
$(selector).goTo();
});

Related

javascript function stops working after div refresh [duplicate]

This question already has answers here:
Event binding on dynamically created elements?
(23 answers)
Closed 5 years ago.
$(function() {
$(".reqdeb").click(function() {
console.log("Working");
var req_id = $(this).attr("id");
var info = 'id=' + req_id;
if (confirm("Are you sure you want to delete this request?")) {
$.ajax({
cache : false,
type : "POST",
url : "del_req.php",
data : info,
success : function() {
}
});
$(this).parents("tr").animate("fast").animate({
opacity : "hide"
}, "slow");
}
return false;
});
});
This is the code that stops working after a few tries of pressing the button and the code that causes it to stop working is this:
function autoRefresh_div(){
$("#refresh").load("reqs.php");
$("#nrref").load("numreq.php")
}
setInterval('autoRefresh_div()', 5000);
Seems you are replacing the existing elements thus event handlers are also removed. You can use .on() method with Event Delegation approach.
General Syntax
$(document).on('event','selector',callback_function)
Example
$(document).on('click', ".reqdeb", function(){
//Rest of your code
});
In place of document you should use closest static container for better performance.

How make javascript function work only one time

How to make Javascript function work only one time ?
if (window.location.hash) {
$(document).ready(function () {
var id = window.location.hash;
$(id).trigger('click');
});
$('li').click(function () {
$(this).prependTo($(this).parent());
});
}
I need auto-click on that li element which link user comes to website. web.com/#2 (list order - 2 1 3 4 5) , web.com/#4 (list order - 4 1 2 3). but i want than user stay in website with hash url list elements stay in their places then user click for example on 3 list element he must stay and his place so list order (4 1 2 3). I just need change list order by url hash on load page.
I solved it
if (window.location.hash) {
$('li').one('click',function () {
if (!window.run){
$(this).prependTo($(this).parent());
window.run = true;
}
});
$(document).ready(function () {
var id = window.location.hash;
$(id).trigger('click');
});
}
In your particular case the simplest solution is to use .one(), which unbinds the handler after running it the first time:
$('li').one('click',function () { ... }
Another approach is to have the function redefine itself to a no-op after it runs. This can be useful in some cases when there isn't a convenient event handler to unbind:
var oneTimeFunction = function() {
console.log("This will only happen once.");
oneTimeFunction = function() {};
}

How to stop toggling classes [duplicate]

This question already has answers here:
Stop setInterval call in JavaScript
(7 answers)
Closed 7 years ago.
This is how I started toggling classes:
$(document).ready(function() {
window.setInterval(function() {
$('.blinkClass').toggleClass('blink');
}, 500);
});
How can I stop toggling these classes?
You need to store the timer returned from setInterval to a variable which you can then use in a call to clearInterval():
var timer = window.setInterval(function() {
$('.blinkClass').toggleClass('blink');
}, 500);
// later on, in a code block within scope of the above variable...
clearInterval(timer);
You can do this :
$(document).ready(function() {
var myVar = window.setInterval(function() {
$('.blinkClass').toggleClass('blink');
}, 500);
//when you want
myStopFunction(myVar)
});
function myStopFunction(par) {
clearInterval(par);
}
See more info at
setInterval
clearinterval

Using .style.opacity = using javascript is not working for some reason

I'm new to javascript and jquery and I am trying to make a video's opacity change when I mouseover a li item. I know 'onmouseover' works because I have tested using the same jquery I use to scroll to the top of the page onclick.
The problem seems to be the syntax to check and update the style of the video div is not working. I adapted the code from a lesson on codeacademy and don't see why it work:
window.onload = function () {
// Get the array of the li elements
var vidlink = document.getElementsByClassName('video');
// Get the iframe
var framecss = document.getElementsByClassName('videoplayer1');
// Loop through LI ELEMENTS
for (var i = 0; i < vidlink.length; i++) {
// mouseover function:
vidlink[i].onmouseover = function () {
//this doesn't work:
if (framecss.style.opacity === "0.1") {
framecss.style.opacity = "0.5";
}
};
//onclick function to scroll to the top when clicked:
vidlink[i].onclick = function () {
$("html, body").animate({
scrollTop: 0
}, 600);
};
}
};
Here is a jsfiddle you can see the html and css:
http://jsfiddle.net/m00sh00/CsyJY/11/
It seems like such a simple problem so I'm sorry if I'm missing something obvious.
Any help is much appreciated
Try this:
vidlink[i].onmouseover = function () {
if (framecss[0].style.opacity === "0.1") {
framecss[0].style.opacity = "0.5";
}
};
Or alternatively:
var framecss = document.getElementsByClassName('videoplayer1')[0];
Or, better, give the iframe an id and use document.getElementById().
The getElementsByClassName() function returns a list, not a single element. The list doesn't have a style property. In your case you know the list should have one item in it, which you access via the [0] index.
Or, given that you are using jQuery, you could rewrite it something like this:
$(document).ready(function(){
// Get the iframe
var $framecss = $('.videoplayer1');
$('.video').on({
mouseover: function () {
if ($framecss.css('opacity') < 0.15) {
$framecss.css('opacity', 0.5);
}
},
click: function () {
$("html, body").animate({
scrollTop: 0
}, 600);
}
});
});
Note that I'm testing if the opacity is less than 0.15 because when I tried it out in your fiddle it was returned as 0.10000000149011612 rather than 0.1.
Also, note that the code in your fiddle didn't run, because by default jsfiddle puts your JS in an onload handler (this can be changed from the drop-down on the left) and you then wrapped your code in window.onload = as well. And you hadn't selected jQuery from the other drop-down so .animate() wouldn't work.
Here's an updated fiddle: http://jsfiddle.net/CsyJY/23/

Refactoring Code

Let's say I have the following code:
$(function () {
$(".buy-it-now.ribbon").click(function () {
$(".bid-to-beat.ribbon.active").removeClass("active");
$(".bid-to-beat.ribbon").addClass("inactive");
$(".buy-it-now.ribbon.inactive").removeClass("inactive");
$(".buy-it-now.ribbon").addClass("active");
$(".bid-now").hide();
$(".buy-now").show();
$(".add-to-cart").hide();
})
$(".bid-to-beat.ribbon").click(function () {
$(".buy-it-now.ribbon.active").removeClass("active");
$(".buy-it-now.ribbon").addClass("inactive");
$(".bid-to-beat.ribbon").removeClass("inactive");
$(".bid-to-beat.ribbon").addClass("active");
$(".buy-now").hide();
$(".bid-now").show();
$(".add-to-cart").show();
});
});
It is a simple function that allows for multiple UI related things to happen on the front-end of a site I am working on. I am fairly (very) new to jQuery and JavaScript in general and am learning about refactoring and making my code more condensed now. The way I currently write code is sort of line per thought I have. So my question is how would an experienced developer write this same code? Or rather, how could I refactor this code?
Try the following:
$(function () {
var $handlers = $('.buy-it-now.ribbon, .bid-to-beat.ribbon');
$handlers.click(function() {
$handlers.toggleClass("active inactive");
var $elements = $(".bid-now, .add-to-cart"),
$buyElement = $(".buy-now");
if($(this).is('.buy-it-now.ribbon')) {
$elements.hide();
$buyElement.show();
} else {
$elements.show();
$buyElement.hide();
}
});
});
This question would be better suited for codereview, but yes it can be condensed a little using method chaining.
$(function () {
$(".buy-it-now.ribbon").click(function () {
$(".bid-to-beat.ribbon").removeClass("active").addClass("inactive");
$(".buy-it-now.ribbon").removeClass("inactive").addClass("active");
$(".bid-now").hide();
$(".buy-now").show();
$(".add-to-cart").hide();
})
$(".bid-to-beat.ribbon").click(function () {
$(".buy-it-now.ribbon").removeClass("active").addClass("inactive");
$(".bid-to-beat.ribbon").removeClass("inactive").addClass("active");
$(".buy-now").hide();
$(".bid-now").show();
$(".add-to-cart").show();
});
});
You could condense it further by pre selecting the elements and caching them in variables before the click events as long as no elements are added or removed during the life of the page.
As your code it is you can combine some of the selectors into a single line. And also because your elements looks to be static you can cache them into a variable and use them later as it reduces the number of times a element is looked up in the DOM reducing the accessing time..
Also you can limit the scope of these variables or selectors by encasing them in an object or a closure..
Maybe something in these lines..
$(function () {
cart.init();
});
var cart = {
elems : {
$buyRibbon : null,
$bidRibbon : null,
$bidNow: null,
$buyNow: null,
$addToCart: null
},
events : {
},
init : function() {
this.elems.$buyRibbon = $(".buy-it-now.ribbon");
this.elems.$bidRibbon = $(".bid-to-beat.ribbon");
this.elems.$bidNow = $(".bid-now") ;
this.elems.$buyNow = $(".buy-now") ;
this.elems.$addToCart = $(".add-to-cart") ;
this.events.buyClick();
this.events.bidClick();
}
};
cart.events.buyClick = function() {
cart.elems.$buyRibbon.on('click', function(){
cart.elems.$bidRibbon.removeClass('active').addClass('inactive');
cart.elems.$buyRibbon.removeClass('inactive').addClass('active');
cart.elems.$bidNow.hide();
cart.elems.$buyNow.show();
cart.elems.$addToCart.hide();
});
}
cart.events.bidClick = function() {
cart.elems.$bidRibbon.on('click', function(){
cart.elems.$buyRibbon.removeClass('active').addClass('inactive');
cart.elems.$bidRibbon.removeClass('inactive').addClass('active');
cart.elems.$bidNow.show();
cart.elems.$buyNow.hide();
cart.elems.$addToCart.show();
});
}
So basically in here your whole cart is a object ..And the cart has different properties which are related to this.. You follow the principles of object oriented programming here..
Using closures I heard gives you better design limiting the scope of your code..
Might I suggest something like this:
$(function () {
var buyNowButton = $('buy-it-now.ribbon'),
bidToBeatButton = $('.bid-to-beat.ribbon'),
buyNowEls = $('.buy-now'),
bidToBeatEls = $('.bid-now,.add-to-cart');
var toggleButtons = function(showBuyNow){
buyNowButton.toggleClass('active', showBuyNow);
bidToBeatButton.toggleClass('active', !showBuyNow);
buyNowEls.toggle(showBuyNow);
bidToBeatEls.toggle(!showBuyNow);
}
buyNowButton.click(function(){ toggleButtons(true) });
bidToBeatButton.click(function(){ toggleButtons(false) });
});
You could save a some lines by removing the selectors at the start and just do the selection in place, if the saved space would be more important than the minor performance hit. Then it would look like this:
$(function () {
var toggleButtons = function(showBuyNow){
$('buy-it-now.ribbon').toggleClass('active', showBuyNow);
$('.bid-to-beat.ribbon').toggleClass('active', !showBuyNow);
$('.buy-now').toggle(showBuyNow);
$('.bid-now,.add-to-cart').toggle(!showBuyNow);
}
$('buy-it-now.ribbon').click(function(){ toggleButtons(true) });
$('.bid-to-beat.ribbon').click(function(){ toggleButtons(false) });
});
The first version selects the elements once and holds them in memory; the second selects them each time the button is clicked. Both solve the problem I believe would occur with the selected answer where clicking the same button twice would cause the .active and .inactive classes to get out of sync with the shown/hidden elements.

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