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JavaScript/jQuery code optimization

I'm learning JavaScript and jQuery and currently I'm dealing with following code:
$("#hrefBlur0").hover(function() {
$("#imgBlur0").toggleClass("blur frame");
});
$("#hrefBlur1").hover(function() {
$("#imgBlur1").toggleClass("blur frame");
});
$("#hrefBlur2").hover(function() {
$("#imgBlur2").toggleClass("blur frame");
});
$("#hrefBlur3").hover(function() {
$("#imgBlur3").toggleClass("blur frame");
});
$("#hrefBlur4").hover(function() {
$("#imgBlur4").toggleClass("blur frame");
});
$("#hrefBlur5").hover(function() {
$("#imgBlur5").toggleClass("blur frame");
});
$("#hrefBlur6").hover(function() {
$("#imgBlur6").toggleClass("blur frame");
});
$("#hrefBlur7").hover(function() {
$("#imgBlur7").toggleClass("blur frame");
});
The code is supposed to remove blur effect from an image while I hoover a cursor on a href link on the website. I'm wondering if I can do it faster, with fewer lines of code.
I tried:
for (var i = 0; i < 8; i++) {
$("#hrefBlur" + i).hover(function() {
$("#imgBlur" + i).toggleClass("blur frame");
});
}
But that code doesn't work.
Here's the JS fiddle: link

You can set a class to the elements and select that class, for example let's say you want to use "blurMeContainer" for the container, you can do something like this:
$(".blurMeContainer").hover(function(el){
$(this).find("img").toggleClass("blur frame");
});
The trick is that you must be aware that jQuery applies the events to the element, so inside the events function, the "this" accessor is the element involved in the event, than you can use the $ function in the selector in order to have his corrispective jQuery element, and then you can use "find" method to find any img tag inside the jQuery element. Obviously this could work only if you have a single image in the container, if you need to identify only one image in a set of images inside a single container, assign a class to that image (IE: "blurMe") and change the code in this way:
$(".blurMeContainer").hover(function(el){
$(this).find(".blurMe").toggleClass("blur frame");
});

Use attributeStartsWith selector , that Selects elements that have the specified attribute with a value beginning exactly with a given string:
$('a[id^="hrefBlur"]').hover(function() {
$(this).find('img').toggleClass("blur frame");
});
Here's working fiddle

Although doing what your after can be done with JQuery. I personally think it's the wrong tool for the Job.
CSS, will do all this for you, in a much simpler way. No Javascript needed. With the added benefit of the browser optimisations.
.blurme {
filter: blur(3px);
cursor: pointer;
transition: color 2s, filter 1s;
}
.blurme:hover {
filter: none;
color: red;
font-weight: bold;
}
<span class="blurme">One</span>
<span class="blurme">Two</span>
<span class="blurme">Three</span>
<span class="blurme">Four</span>
<span class="blurme">Five</span>
<span class="blurme">Six</span>
<br>
<img class="blurme" src="http://placekitten.com.s3.amazonaws.com/homepage-samples/96/139.jpg">
<img class="blurme" src="http://placekitten.com.s3.amazonaws.com/homepage-samples/96/139.jpg">
<img class="blurme" src="http://placekitten.com.s3.amazonaws.com/homepage-samples/96/139.jpg">

ng-mouseover ng-mouseout not woking

below is my code, I'm trying to make the content wrapped in div tag change the background color when the mouse curse over it, if the one of the content's variable starts with *. But it doesn't work...
// html
<style>
.normal{background-color: white}
.change{background-color: gainsboro}
</style>
<div ng-mouseover="checkAs(this)" ng-mouseout="this.className='normal'">
......
</div>
// js
$scope.checkAs = function(obj) {
var name = $scope.opportunity.name;
var asterisk = '*';
if(name.startsWith(asterisk)) {
obj.className='change';
} else {
obj.className='normal';
}
};

If you are determined to do this in angular, you would have to call a function through ng-mouseover and in that function, you would need a selector such as JQuery or Javascript's query selector, then modify the element as you see fit. You would have to do something like this (using JQuery):
$scope.checkAs = function() {
$("div").hover(function() {
$(this).prop('background-color','gainsboro');
}, function(){
$(this).prop('background-color','white');
});
};
But, as PSL suggested, the "this" in checkAs(this) won't be the DOM element. A CSS solution might be better:
div :hover{
background-color: gainsboro
}

Can this JQuery code be written using plain Javascript?

Is there a way to represent this code as plain vanilla Javascript so I can better understand how it works for now?
$("#id").click(function(){
var $x = $("#id");
$x.removeProp("-webkit-animation");
});
Essentially I'm using this to tell the code not to play a css animation given that a certain set of parameters are met.

removeProp removes properties of objects. If that’s definitely what you want, the equivalent is the delete operator:
var element = document.getElementById("id");
element.addEventListener("click", function () {
delete element["-webkit-animation"];
});
If what you really want to do is change a CSS property, though, it needs to be an operation on the element’s style:
element.style.WebkitAnimation = "none";
But what you should probably do is change a class instead:
element.classList.add("no-animation");
and use CSS:
.no-animation {
-webkit-animation: none;
}

The delete element is the somewhat equivalent on vanilla javascript of removeProp()
element = document.getElementById('id');
element.onclick() = function(){
delete element['-webkit-animation'];
}

Yes, you can use the .removeAttribute() function to remove an attribute, like style, title, etc.
Or you can use .removeProperty() to remove a style property (supported in IE9 and above)
Fiddle
(function() {
var myDiv = document.getElementById('myDiv');
myDiv.removeAttribute('style');
var aDiv = document.getElementById('aDiv');
aDiv.style.removeProperty('height');
})();
<div id="aDiv" style="background-color: green;">Hi</div>
<div id="myDiv" style="background-color: green;">Hi</div>

Hope it will help OP
JS
var element = document.getElementById("id");
element.onClick = function(){
this.style.removeProperty("-webkit-animation");
};

How to change CSS pseudo-class element using JavaScript

I want to change this image using javascript:
dance:active { background-image: url("myImage.png") }
You can use
document.getElementById(element).style.backgroundImage = url(image);
to change
#element {background-image: url(image)}
I would like to change the image of when the element is active using javascript. Thanks!

I figured it out!
You can have multiple classes in your CSS :
element.dance1 { stuff }
element.dance1:active { active stuff }
element.dance2 { stuff 2 }
element.dance2:active { active stuff 2 }
and then change the class of the element in javascript:
document.getElementById(element).className = dance1/dance2

You can try using jQuery to achive what you want. dance: active is CSS Pseudo-classes. Learn more about Pseudo-class.
The demo change the div color when mouse down and switch the color back when mouse up. Leave comments if this is not what you want.
$("#dance").on("mousedown", function () {
$("#dance").css("background", "blue");
}).on("mouseup", function(){
$("#dance").css("background", "black");
});
https://jsfiddle.net/x_li/5nkvms8q/
and jQuery can also do the following
$('#damce:checked').val();

jQuery changed ID won't run function

I'm trying to make a blue div that turns red when clicking on it and the red div turns back to blue ( so I can add more events on the click after clicking, so .css isn't really an option)
When clicking on the div when it's blue, it turns red. But when I click the red div it doesn't respond, even when I add a simple alert()
Does anyone know what I'm doing wrong?
This is my current code and a JSFiddle
code:
$("#Blue").click(function(){
$("#Blue").attr("id","Red");
});
$("#Red").click(function(){
$("Red").attr("id","Blue");
});
If anyone could tell me what Exactly I'm doing wrong that would be great, thank you in advance

You need to use event delegation -- your click handlers are bound to the matching elements at the time the code is first run, and only then. Since there's no #Red element at that point in time, that second click handler isn't bound to anything.
$(document).on('click',"#Blue", function(){
$("#Blue").attr("id","Red");
});
$(document).on('click',"#Red", function(){
$("#Red").attr("id","Blue");
});
http://jsfiddle.net/mblase75/HDFyn/
http://api.jquery.com/on
That said, the "proper" way to do this would be to add and remove a class, not change the ID:
$('#btn').on('click', function(){
$(this).toggleClass("red blue");
});
http://jsfiddle.net/mblase75/mKMW6/

.click() binds only to existing elements at the time you call it; it will not bind to a later-created element or an element to which you assign the id later.
The fix is to use event delegation. See here and here for more information.
Also, use classes, instead -- much more flexible.

HTML
<div class="Test blue">Test</div>
jQuery
$(".blue, .red").click(function(){
$(this).toggleClass('red blue')
});
CSS
.Test{
width: 50px;
height: 50px;
}
.blue{
background-color: blue;
}
.red{
background-color: red;
}
Fiddle: http://jsfiddle.net/8FmSt/3/

You could use the class and update the ID like below instead of having 2 function to do that action,
$('.Test').on('click', function () {
this.id = (this.id == 'Blue')?'Red':'Blue';
});
DEMO: http://jsfiddle.net/8FmSt/2/
If it is all about changing color, then use a css to change to color like below,
$('.Test').on('click', function () {
$(this).toggleClass('Red Blue');
});
http://jsfiddle.net/8FmSt/5/

Try:
$(".Test").click(function(){
var id = $(this).attr("id");
if(id == "Red"){
$(this).attr("id","Blue");
}
else{
$(this).attr("id","Red");
}
});
Updated fiddle here.

Let's uncomplicate
HTML
<div class="Test">Test</div>
JQUERY
$(".Test").on('click', function () {
$(this).toggleClass("red");
});
CSS
.Test {
width: 50px;
height: 50px;
background: blue;
}
.red {
background: red;
}