Develop Reference

JavaScript - function can't acces variables from another function scope

I am trying to create a slider with javscript. I would like to have two functions - first of them, parseDom(), should be responsible for getting elements from DOM; the second one, configureRange(), should be responsible for setting range attributes, like min and max values. Both functions are called inside anonymous function, which is assigned to window.onload variable.
function parseDom() {
var main = document.getElementById('main');
main.classList.add('red');
// red class added - main selector is ok
var rangeContainer = main.querySelector('.range-container');
rangeContainer.classList.add('green');
// green class added - rangeContainer selector is ok
var rangeInput = rangeContainer.querySelector('.range-input');
rangeInput.classList.add('crosshair');
// crosshair class added - rangeInput selector is ok
}
function configureRange(){
rangeInput.classList.add('pointer');
rangeInput.setAttribute('min', '0');
}
window.onload = function(){
parseDom();
configureRange();
}
However, variables from parseDom() can't be accesed from configureRange(), because variables inside these functions are in different scopes. So my code inside configureRange() does not work. I could do all things in one function instead of two, but this would make code messy. How do I create a good modular solution?
Code is here:
https://codepen.io/t411tocreate/pen/oeKwbW?editors=1111

The simplest thing is probably to pass configureRange the information it needs, by having parseDom call it:
function parseDom() {
var main = document.getElementById('main');
main.classList.add('red');
// red class added - main selector is ok
var rangeContainer = main.querySelector('.range-container');
rangeContainer.classList.add('green');
// green class added - rangeContainer selector is ok
var rangeInput = rangeContainer.querySelector('.range-input');
rangeInput.classList.add('crosshair');
// crosshair class added - rangeInput selector is ok
configureRange(rangeInput); // <==== Added call
}
function configureRange(rangeInput){ // <==== Note new parameter
rangeInput.classList.add('pointer');
rangeInput.setAttribute('min', '0');
}
window.onload = function(){
parseDom();
// <==== Removed call
}
...or by having a controller function (parseAndConfigure, whatever) that looks up the input and passes it to both functions.
Side note: In terms of keeping functions small and ensuring the name is indicative of what it does (as seems to be your goal), parseDom doesn't parse anything, and it does more than just identify the relevant DOM elements (it also adds classes to them). Perhaps three functions: getDom, addClasses, and configureRange or similar. Then:
window.onload = function() {
var dom = getDom();
addClasses(dom);
configureRange(dom);
}
...or something like that.

You could keep the elements in an object, and then return that object, to be reused anywhere else
function parseDom() {
var els = (function(d) {
var main = d.getElementById('main'),
rangeContainer = main.querySelector('.range-container'),
rangeInput = rangeContainer.querySelector('.range-input');
return {main, rangeContainer, rangeInput};
})(document);
els.main.classList.add('red');
els.rangeContainer.classList.add('green');
els.rangeInput.classList.add('crosshair');
return els;
}
function configureRange(els) {
els.rangeInput.classList.add('pointer');
els.rangeInput.setAttribute('min', '0');
return els;
}
window.onload = function() {
var elems = parseDom();
configureRange(elems);
}

simplest approach would be to abstract the selectors away from the parseDom function, maybe call that updateDom instead and parse the selectors in the top level function e.g.
function updateDom(main, rangeContainer, rangeInput) {
main.classList.add('red');
// red class added - main selector is ok
rangeContainer.classList.add('green');
// green class added - rangeContainer selector is ok
rangeInput.classList.add('crosshair');
// crosshair class added - rangeInput selector is ok
}
function configureRange(rangeInput){
rangeInput.classList.add('pointer');
rangeInput.setAttribute('min', '0');
}
window.onload = function(){
var main = document.getElementById('main'),
rangeContainer = main.querySelector('.range-container'),
rangeInput = rangeContainer.querySelector('.range-input');
updateDom(main, rangeContainer, rangeInput);
configureRange(rangeInput);
}

You could declare your variables inside the .onload, then pass them as arguments to as many functions as you like:
function parseDom(main, rangeContainer, rangeInput) { // <= arguments
main.classList.add('red');
rangeContainer.classList.add('green');
rangeInput.classList.add('crosshair');
}
function configureRange(rangeInput){ // <= argument
rangeInput.classList.add('pointer');
rangeInput.setAttribute('min', '0');
}
window.onload = function(){
var main = document.getElementById('main'),
rangeContainer = main.querySelector('.range-container'),
rangeInput = rangeContainer.querySelector('.range-input'),
// other elements
parseDom(main, rangeContainer, rangeInput); // <= pass as arguments
configureRange(rangeInput); // <= pass as argument
}

How can I refresh a stored and snapshotted jquery selector variable

I ran yesterday in a problem with a jquery-selector I assigned to a variable and it's driving me mad.
Here is a jsfiddle with testcase:
assign the .elem to my obj var
log both lengths to the console. Result => 4
Remove #3 from the DOM
log obj to the console => the removed #3 is still there and the length is still 4.
I figured out that jquery query is snapshotted? to the variable and can't?won't? be updated
log .elem to the console.. yep Result => 3 and the #3 is gone
Now I update .elem with a new width of 300
logging obj & obj.width gives me 300.. So the snapshot has been updated ? What's interesting is that 3 of the 4 divs have the new width, but the removed #3 doesn't...
Another test: Adding a li element to the domtree and logging obj and .elem.
.elem does have the new li and obj doesn't, because it's still the old snapshot
http://jsfiddle.net/CBDUK/1/
Is there no way to update this obj with the new content?
I don't want to make a new obj, because in my application there is a lot information saved in that object, I don't want to destroy...

Yeah, it's a snapshot. Furthermore, removing an element from the page DOM tree isn't magically going to vanish all references to the element.
You can refresh it like so:
var a = $(".elem");
a = $(a.selector);
Mini-plugin:
$.fn.refresh = function() {
return $(this.selector);
};
var a = $(".elem");
a = a.refresh();
This simple solution doesn't work with complex traversals though. You are going to have to make a parser for the .selector property to refresh the snapshot for those.
The format is like:
$("body").find("div").next(".sibling").prevAll().siblings().selector
//"body div.next(.sibling).prevAll().siblings()"
In-place mini-plugin:
$.fn.refresh = function() {
var elems = $(this.selector);
this.splice(0, this.length);
this.push.apply( this, elems );
return this;
};
var a = $(".elem");
a.refresh() //No assignment necessary

I also liked #Esailija solution, but seems that this.selector has some bugs with filter.
So I modified to my needs, maybe it will be useful to someone
This was for jQuery 1.7.2 didn`t test refresh on filtered snapshots on higher versions
$.fn.refresh = function() { // refresh seletor
var m = this.selector.match(/\.filter\([.\S+\d?(\,\s2)]*\)/); // catch filter string
var elems = null;
if (m != null) { // if no filter, then do the evarage workflow
var filter = m[0].match(/\([.\S+\d?(\,\s2)]*\)/)[0].replace(/[\(\)']+/g,'');
this.selector = this.selector.replace(m[0],''); // remove filter from selector
elems = $(this.selector).filter(filter); // enable filter for it
} else {
elems = $(this.selector);
}
this.splice(0, this.length);
this.push.apply( this, elems );
return this;
};
Code is not so beautiful, but it worked for my filtered selectors.

Clean and generic solution worked properly with jQuery 3.4.1:
My solution is to do the following:
Intercept the selector at the time of jQuery object initialization and in the same time maintain all other jQuery functionalities transparently all this using inheritance
Build refresh plugin that make use of the new "selector" property we added during initialization
Definition:
$ = (function (originalJQuery)
{
return (function ()
{
var newJQuery = originalJQuery.apply(this, arguments);
newJQuery.selector = arguments.length > 0 ? arguments[0] : null;
return newJQuery;
});
})($);
$.fn = $.prototype = jQuery.fn;
$.fn.refresh = function ()
{
if (this.selector != null && (typeof this.selector === 'string' || this.selector instanceof String))
{
var elems = $(this.selector);
this.splice(0, this.length);
this.push.apply(this, elems);
}
return this;
};
Usage:
var myAnchors = $('p > a');
//Manipulate your DOM and make changes to be captured by the refresh plugin....
myAnchors.refresh();
//Now, myAnchors variable will hold a fresh snapshot
Note:
As optimization, object selectors don't need refresh as they are pass by reference by nature so, in refresh plugin, we only refresh if the selector is a string selector not object selector for clarification, consider the following code:
// Define a plain object
var foo = { foo: "bar", hello: "world" };
// Pass it to the jQuery function
var $foo = $( foo );
// Test accessing property values
var test1 = $foo.prop( "foo" ); // bar
// Change the original object
foo.foo = "koko";
// Test updated property value
var test2 = $foo.prop( "foo" ); // koko

Jquery .selector is deprecated, it's better to remeber string with selector value to some variable at the moment when you assign
function someModule($selector, selectorText) {
var $moduleSelector = $selector;
var moduleSelectorText = selectorText;
var onSelectorRefresh = function() {
$moduleSelector = $(moduleSelectorText);
}
}
https://api.jquery.com/selector/

You can also return the JQuery selector in a function, and save this function into the variable. Your code will look a bit different but it works. Every time when you execute the function, your jquery selector will search the DOM again.
In this example I used an arrow function without brackets which will return whatever is next to arrow. In this case it will return the JQuery collection.
const $mySelector = () => $('.selector');
console.log($mySelector().last().text());
$('.parent').append('<li class="selector">4</li>')
console.log($mySelector().last().text()); //RETURNS 4 not 3
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<ul class="parent">
<li class="selector">1</li>
<li class="selector">2</li>
<li class="selector">3</li>
</ul>

If you use remove() it will remove only a part of the DOM but not all the children or related, instead if you use empty() on the element the problem is gone.
E.G.:
$('#parent .child).find('#foo').empty();
Maybe it can be useful to someone!

jQuery - why can't I bind events to elements in a loop?

Here is my code:
var b = $(slipStream.conf.mainVis).find('p#prev');
b.click(function() {
slipStream.slideLeft();
return false;
});
b = $(slipStream.conf.mainVis).find('p#next');
b.click(function() {
slipStream.slideRight();
return false;
});
b = $(slipStream.conf.controls).find('li img');
console.log(b);
for (var l in b) {
l.click(function() {
var visIndex = l.index();
console.log(visIndex);
});
};
The first two bindings go through, no problem. But I can't loop through a collection and bind something to each member? (the console is telling me that "l.click is not a function.") Is this a limitation of jQuery or is my code off? This seems like it would be the way to do it, though...

When you enumerate over a jQuery object, the values being enumerated are actual DOM nodes and not jQuery wrappers. Therefore, they don't have a click method but you can wrap them again to get all the usual functionality.
Of course this is not necessary because you can simply attach a wrapper directly from your initial jQuery instance:
$(slipStream.conf.controls).find('li img').click(function() {
var visIndex = $(this).index();
console.log(visIndex);
});

This is the classic "loop variables don't work properly in callbacks" bug.
Your variable l no longer has the originally supplied value by the time the callback is invoked - it has whatever final value was assigned in the last pass through the loop.
[FWIW, l isn't actually a jQuery object, so you have to wrap it - $(l) to use it with jQuery]
The usual fix to the loop bug is to create an additional closure that returns a function bound to the current value:
for (var l in b) { // NB: don't use `for ... in ...` on array-like objects!
var make_cb = function(n) {
return function() {
var visIndex = $(n).index();
console.log(visIndex);
}
}
$(l).click(make_cb(l));
};
Fortunately, you don't need a loop at all - you can have jQuery automatically add the callback to every element by itself:
b = $(slipStream.conf.controls).find('li img');
b.click(function() {
var visIndex = $(this).index();
console.log(visIndex);
});

Could it be that the problem is the forloop. .click is part of the jQuery, so you must be sure that it's called on element that is wrapper with jQuery.
$.each(b, function (index, element) {
$(element).click(function() {
});
};

With each() you can iterate through a set of jQuery objects:
$(slipStream.conf.controls).find('li img').each(function(){
$(this).click(function() {
var visIndex = $(this).index();
console.log(visIndex);
});
});
$(this) will match the currently indexed object from the collection.

remove elements from the jQuery object from within a plugin

I think I have mistaken some fundamentals here, because I think this should work. I am trying to to through the child p and div elements of the matched set, and remove those which fail to meet the required wordcount from the matched set.
I have tested the wordCount plugin, and the if statement it is being used it, and all seems to be working fine, but my element is not being removed from the matched set.
(function($){
$.fn.extend({
textBlocks: function(count){
var JQ_Object = $(this);
if(!count) count = 100;
return this.each(function(){
$(this).find("p, div").each(function(){
if($(this).wordCount()<count){
var x = $(this);
JQ_Object.not(x);
};
});
return JQ_Object;
});
}
});
})(jQuery);
Here is the wordCount plugin, just in case you wondered:
(function($){
$.fn.extend({
wordCount: function(){
return $(this).html().split(" ").length;
}
});
})(jQuery);

I made a few changes... see fiddle for working example and code for comments.
http://jsfiddle.net/8PXpt/
(function ($){
$.fn.extend({
wordCount: function (){
//Don't need $(this), this already refers to the jQuery object
//Always trim .html() and .text() when using .split()
//May want to use .text() instead of .html() - I leave that to you
return $.trim(this.html()).split(' ').length;
}
});
})(jQuery);
(function ($){
$.fn.extend({
textBlocks: function (count){
var collection = this;
//Check that a number was passed
//"50" would break your extension
if(typeof count !== 'number') {
count = 100;
}
//Removed $('div, p') - this should be part of your call
//See ready function below
this.each(function (){
if ($(this).wordCount() < count){
//This could be double assignment
//but better safe than sorry
collection = collection.not(this);
};
});
//Return what is left (what passed)
return collection ;
}
});
})(jQuery);
$(function() {
//Here is where you define your selector... in your case 'div, p'
$('div, p').textBlocks(2);
});

Have you tried $(this).remove() rather than JQ_Object.not(x);
I think .not() removes them from the selection rather than from the HTML... unless that's what you're trying to do

You're creating a new JQ_Object in the internal each, so I'm not sure if it would modify the original JQ_Object. I'm not 100% on that though. Try JQ_Object.not(this).
This assumes, however, that .each is synchronous, which I'd hope it isn't. If that's the case, you'd need to make use of jQuery's while function.
This should give you the desired result, but I'd be wary each being asynchronous.
return $(this).find("p, div").each(function(){
if($(this).wordCount()<count){
JQ_Object.not(this);
};
});
EDIT:
I'm not to sure about the above code. What I'd do is use a callback. This assumes a callback is passed in to your plugin.
$(this).find("p, div").each(function(){
if($(this).wordCount()<count){
JQ_Object.not(this);
};
}).when(function () {
callback(JQ_Object);
});

call function inside a nested jquery plugin

There are many topics related to my question and i have been through most of them, but i haven't got it right. The closest post to my question is the following:
How to call functions that are nested inside a JQuery Plugin?
Below is the jquery plugin i am using. On resize, the element sizes are recalculated. I am now trying to call the function resizeBind() from outside of the jquery plugin and it gives me error
I tried the following combinations to call the function
$.fn.splitter().resizeBind()
$.fn.splitter.resizeBind()
Any ideas, where i am getting wrong?
;(function($){
$.fn.splitter = function(args){
//Other functions ......
$(window).bind("resize", function(){
resizeBind();
});
function resizeBind(){
var top = splitter.offset().top;
var wh = $(window).height();
var ww = $(window).width();
var sh = 0; // scrollbar height
if (ww <0 && !jQuery.browser.msie )
sh = 17;
var footer = parseInt($("#footer").css("height")) || 26;
splitter.css("height", wh-top-footer-sh+"px");
$("#tabsRight").css("height", splitter.height()-30+"px");
$(".contentTabs").css("height", splitter.height()-70+"px");
}
return this.each(function() {
});
};
})(jQuery);

I had the same problem. Those answers on related posts didn't work for my case either. I solved it in a round about way using events.
The example below demonstrates calling a function that multiplies three internal data values by a given multiplier, and returns the result. To call the function, you trigger an event. The handler in turn triggers another event that contains the result. You need to set up a listener for the result event.
Here's the plugin - mostly standard jQuery plugin architecture created by an online wizard:
(function($){
$.foo = function(el, options){
// To avoid scope issues, use 'base' instead of 'this'
var base = this;
// Access to jQuery and DOM versions of element
base.$el = $(el);
base.el = el;
// Add a reverse reference to the DOM object
base.$el.data("foo", base);
base.init = function(){
base.options = $.extend({},$.foo.defaultOptions, options);
// create private data and copy in the options hash
base.private_obj = {};
base.private_obj.value1 = (base.options.opt1);
base.private_obj.value2 = (base.options.opt2);
base.private_obj.value3 = (base.options.opt3);
// make a little element to dump the results into
var ui_element = $('<p>').attr("id","my_paragraph").html(base.private_obj.value1 +" "+ base.private_obj.value2+" " +base.private_obj.value3);
base.$el.append(ui_element);
// this is the handler for the 'get_multiplied_data_please' event.
base.$el.bind('get_multiplied_data_please', function(e,mult) {
bar = {};
bar.v1 = base.private_obj.value1 *mult;
bar.v2 = base.private_obj.value2 *mult;
bar.v3 = base.private_obj.value3 *mult;
base.$el.trigger("here_is_the_multiplied_data", bar);
});
};
base.init();
}
$.foo.defaultOptions = {
opt1: 150,
opt2: 30,
opt3: 100
};
$.fn.foo = function(options){
return this.each(function(){
(new $.foo(this, options));
});
};
})(jQuery);
So, you can attach the object to an element as usual when the document is ready. And at the same time set up a handler for the result event.
$(document).ready(function(){
$('body').foo();
$('body').live('here_is_the_multiplied_data', function(e, data){
console.log("val1:" +data.v1);
console.log("val2:" +data.v2);
console.log("val3:" +data.v3);
$("#my_paragraph").html(data.v1 +" "+ data.v2+" " +data.v3);
});
})
All that's left is to trigger the event and pass it a multiplier value
You could type this into the console - or trigger it from a button that picks out the multiplier from another UI element
$('body').trigger('get_multiplied_data_please', 7);
Disclaimer ;) - I'm quite new to jQuery - sorry if this is using a hammer to crack a nut.

resizeBind function is defined as private so you cannot access it from outside of it's scope. If you want to use it in other scopes you need to define it like that
$.fn.resizeBind = function() { ... }
Then you would call it like that $(selector').resizeBind()

You have defined the resizeBind function in a scope that is different from the global scope. If you dont'use another javascript framework or anything else that uses the $ function (to prevent conflict) you can delete the
(function($){
...
})(jQuery);
statement and in this way the function will be callable everywhere without errors

I didn't test it:
this.resizeBind = function() { .... }