Changing the state of a toggle in JavaScript/jQuery - javascript

Is it possible to change the state of a toggle function? Like:
myDiv.toggle ... function 1 , function 2
I click on the myDiv element, the function 1 executes
I click again, function 2
I click again, function 1
BUT
Change the state
function 1 again
etc.
But I need to be able to change the state from outside the toggle function.

Here is a javascript object that uses closure to track it's state and toggle:
var TOGGLER = function() {
var _state = true;
var _msg = "function1";
var function1 = function() {
_msg = "function1";
}
var function2 = function() {
_msg = "function2";
}
return {
toggle: (function () {
_state = !_state;
if (_state) {
function1();
} else {
function2();
}
return _msg;
})
}
}();
Here is a jsfiddle that shows how to use it to toggle based with the following jquery: http://jsfiddle.net/yjPKH/5/
$(document).ready(function() {
$("#search").click(function() {
var message = TOGGLER.toggle();
$("#state").text(message);
});
});

The toggle function is meant for simple use cases. Changing the state externally is not "simple" anymore.
You cannot easily/safely (it's internal so it may change during minor versions) access the state variable of the toggle function easily as it's stored in the internal dataset of the element.
If you really want to do it, you can try this code though:
$._data(ELEMENT, "lastToggle" + func.guid, 0);
func is the function you passed to .toggle(), so you need to save this function in a variable. Here's a minimal example: http://jsfiddle.net/xqgrP/
However, since inside the function there's a var guid = fn.guid || jQuery.guid++ statement, I somehow think that the devs actually meant to use guid instead of func.guid for the _data key - in that case a minor update is very likely to break things. And after the fix you'd have to iterate over the data set to retrieve the correct key as there is no way to access the guid from outside.

Related

How do you use Javascript constructor methods in a jQuery statement?

I can't figure out how to use a Javascript constructor method in a jQuery .click method. I'm trying to get a button's function to change dynamically based on a constructor. Here's the set up:
<button onclick="">
</button>
needs to call a method that changes depending on another button. The following is my broken code:
function GloveMode (name , array) {
this.colorArray = array;
this.displaySettings = function(){
//Title
$("#displayTitle").text(this.name);
//Display Color Set
$("#displayColors").empty();
//Totally Broken
$("#upArrow").click( function(){
addColor();
});
};
this.addColor = function(){
console.log(this.colorArray.length);
};
};
I can't figure out how to get $("#upArrow").click() to call this.colorArray properly, or how to call this.addColor() in the .click() method! Please help.
Your Problem is that "this" means something different in each function body. So save the wanted "this" to a variable e.g. "self" and use that.
function GloveMode (name , array)
{
var self = this;
this.colorArray = array;
this.displaySettings = function()
{
//Title
$("#displayTitle").text(this.name);
//Display Color Set
$("#displayColors").empty();
//Totally Broken
$("#upArrow").click( function()
{
self.addColor();
});
};
this.addColor = function()
{
console.log(self.colorArray.length);
};
};

Explicitly scope a variable inside a function vs closure

I have the 'phone_dlg_manager' constructor function and its private methods show and init_country_code_combobox. The dialog reference is held in the phone_dlg variable. The show method triggers init_country_code_combobox and I have two options:
1) Explicitly pass the variable country_combobox that the init_country_code_combobox methods needs:
function phone_dlg_manager(ctx, open_dlg_button, edit_ctrl, item)
{
var phone_dlg;
show();
function show()
{
phone_dlg = ctx.application.ui.create_dialog(0, "PhoneEditorDlg");
init_country_code_combobox(phone_dlg.country);
read_to_dialog_controls(this._form_item);
phone_dlg.visible = true;
}
function init_country_code_combobox(country_combobox)
{
country_combobox.items.clear();
country_combobox.items.start_adding();
country_combobox.items.finish_adding();
}
}
2) Since phone_dlg is accessible withing init_country_code_combobox through closure, I can access the property that I need without explicitly passing the variable:
function phone_dlg_manager(ctx, open_dlg_button, edit_ctrl, item)
{
var phone_dlg;
show();
function show()
{
phone_dlg = ctx.application.ui.create_dialog(0, "PhoneEditorDlg");
init_country_code_combobox(phone_dlg.country);
read_to_dialog_controls(this._form_item);
phone_dlg.visible = true;
}
function init_country_code_combobox()
{
var country_combobox = phone_dlg.country;
country_combobox.items.clear();
country_combobox.items.start_adding();
country_combobox.items.finish_adding();
}
}
The second option seems easier to understand when reading code, however it makes the init_country_code_combobox function know more than it needs. Which option should I choose?
Thanks
This is mostly a matter of style. Option 1 is a little cleaner, and more extensible, since you can use init_country_code_combobox() to initialize more than just the one dialog. But if this is unlikely to be necessary, option 2 is not unreasonable.

JavaScript global variables declaration

The following script works correctly although I need to make few amends. In each function I am getting the values need for the different formulas. However I tend to replicate the same line of code in different functions.
Ex.
function one(){ var v1= document.getElementById('one').value; }
function two(){ var v1= document.getElementById('one').value; }
Full code
I would like to declare all of the variables once and than only use the ones I need for the specific functions. If I declare them right at the top than once they are called they still hold the original value so I need to update that value to the current one if changed of course.
Your code will be very hard to read if you do it like in your fiddle.
Instead do
var myVars;
window.onload=function() {
myVars = {
'list_price': document.getElementById('list_price'),
'negotiated': document.getElementById('negotiated'),
.
.
'lease_payment': document.getElementById('lease_payment')
}
now you can do
var price = myVars.list_price.value;
or perhaps add a function
function getVal(id) {
var val = document.getElementById(id).value;
if (val =="" || isNaN(val)) return 0;
return parsetInt(val,10);
}
now you can do
var price = getVal("list_price");
mplungjan's solution is a great one. If you're at all concerned by your global vars leaking into the window scope, wrap your code in an Immediately Invoked Function Expression to prevent that from happening:
(function(){
// code goes here
}());
There are two ways to go about this:
Update your variable when the value changes
Use a function that always returns the correct value
1) You can add a listener for the change event or the keyup event that changes your global variable:
// save initial value
var val = document.getElementById('one').value;
// update the value when input is changed
addEventListener(document.getElementById('one'), 'change', function() {
val = document.getElementById('one').value;
});
console.log(val);
2) You can use a function that always returns the current value:
var val = function() { return document.getElementById('one').value; };
console.log(val());
2b) If you hate parenthesis, you can define a property that uses the function above as a getter:
Object.defineProperty(window, 'one', {
get : function() { return document.getElementById('one').value; }
});
console.log(one);

Jquery click bindings are not working correctly when binding multiple copies

I seem to have an issue when creating copies of a template and tying the .click() method to them properly. Take the following javascript for example:
function TestMethod() {
var test = Array();
test[0] = 0;
test[1] = 1;
test[2] = 2;
// Insert link into the page
$("#test_div").html("<br>");
var list;
for (x = 0; x < test.length; x++) {
var temp = $("#test_div").clone();
temp.find('a').html("Item #" + test[x]);
temp.click(function () { alert(x); });
if (list == undefined)
list = temp;
else
list = list.append(temp.contents());
}
$("#test_div2").append(list);
}
The problem I am seeing with this is that no matter which item the user clicks on, it always runs alert(2), even when you click on the first few items.
How can I get this to work?
Edit: I have made a very simple example that should show the problem much clearer. No matter what item you click on, it always shows an alert box with the number 2 on it.
Correct me if I'm wrong, .valueOf() in JS returns the primitive value of a Boolean object.....
this would not happen ShowObject(5,'T');... ShowObject(objectVal.valueOf(), 'T');
why not use objects[x].Value directly? ShowObject(objects[x].Value, 'T');
WOOOOOSSSHHHH!
after searching deeply... I found a solution...
because it's a closure, it won't really work that way...
here's a solution,
temp.find('a').bind('click', {testVal: x},function (e) {
alert(e.data.testVal);
return false;
});
for best explanation, please read this... in the middle part of the page where it says Passing Event Data a quick demo of above code
I think your issue arises from a misunderstanding of scopes in JavaScript. (My apologies if I'm wrong.)
function () {
for (...) {
var foo = ...;
$('<div>').click(function () { alert(foo); }).appendTo(...);
}
}
In JavaScript, only functions create a new scope (commonly referred to as a closure).
So, every round of the for loop will know the same foo, since its scope is the function, not the for. This also applies to the events being defined. By the end of looping, every click will know the same foo and know it to be the last value it was assigned.
To get around this, either create an inner closure with an immediately-executing, anonymous function:
function () {
for (...) {
(function (foo) {
$('<div>').click(function () { alert(foo); }).appendTo(...);
})(...);
}
}
Or, using a callback-based function, such as jQuery.each:
function () {
$.each(..., function (i, foo) {
$('<div>').click(function () { alert(foo); }).appendTo(...);
});
}
For your issue, I'd go with the latter (note the changes of objects[x] to just object):
var list;
jQuery.each(data.objects, function (x, object) {
// Clone the object list item template
var item = $("#object_item_list_template").clone();
// Setup the click action and inner text for the link tag in the template
var objectVal = object.Value;
item.find('a').click(function () { ShowObject(objectVal.valueOf(), 'T'); }).html(object.Text);
// add the html to the list
if (list == undefined)
list = item;
else
list.append(item.contents());
});

Javascript function objects

I edited the question so it would make more sense.
I have a function that needs a couple arguments - let's call it fc(). I am passing that function as an argument through other functions (lets call them fa() and fb()). Each of the functions that fc() passes through add an argument to fc(). How do I pass fc() to each function without having to pass fc()'s arguments separately? Below is how I want it to work.
function fa(fc){
fc.myvar=something
fb(fc)
}
function fb(fc){
fc.myothervar=something
fc()
}
function fc(){
doessomething with myvar and myothervar
}
Below is how I do it now. As I add arguments, it's getting confusing because I have to add them to preceding function(s) as well. fb() and fc() get used elsewhere and I am loosing some flexibility.
function fa(fc){
myvar=something
fb(fc,myvar)
}
function fb(fc,myvar){
myothervar=something
fc(myvar,myothervar)
}
function fc(myvar,myothervar){
doessomething with myvar and myothervar
}
Thanks for your help
Edit 3 - The code
I updated my code using JimmyP's solution. I'd be interested in Jason Bunting's non-hack solution. Remember that each of these functions are also called from other functions and events.
From the HTML page
<input type="text" class="right" dynamicSelect="../selectLists/otherchargetype.aspx,null,calcSalesTax"/>
Set event handlers when section is loaded
function setDynamicSelectElements(oSet) {
/**************************************************************************************
* Sets the event handlers for inputs with dynamic selects
**************************************************************************************/
if (oSet.dynamicSelect) {
var ySelectArgs = oSet.dynamicSelect.split(',');
with (oSet) {
onkeyup = function() { findListItem(this); };
onclick = function() { selectList(ySelectArgs[0], ySelectArgs[1], ySelectArgs[2]) }
}
}
}
onclick event builds list
function selectList(sListName, sQuery, fnFollowing) {
/**************************************************************************************
* Build a dynamic select list and set each of the events for the table elements
**************************************************************************************/
if (fnFollowing) {
fnFollowing = eval(fnFollowing)//sent text function name, eval to a function
configureSelectList.clickEvent = fnFollowing
}
var oDiv = setDiv(sListName, sQuery, 'dynamicSelect', configureSelectList); //create the div in the right place
var oSelected = event.srcElement;
if (oSelected.value) findListItem(oSelected)//highlight the selected item
}
Create the list
function setDiv(sPageName, sQuery, sClassName, fnBeforeAppend) {
/**************************************************************************************
* Creates a div and places a page in it.
**************************************************************************************/
var oSelected = event.srcElement;
var sCursor = oSelected.style.cursor; //remember this for later
var coords = getElementCoords(oSelected);
var iBorder = makeNumeric(getStyle(oSelected, 'border-width'))
var oParent = oSelected.parentNode
if (!oParent.id) oParent.id = sAutoGenIdPrefix + randomNumber()//create an ID
var oDiv = document.getElementById(oParent.id + sWindowIdSuffix)//see if the div already exists
if (!oDiv) {//if not create it and set an id we can use to find it later
oDiv = document.createElement('DIV')
oDiv.id = oParent.id + sWindowIdSuffix//give the child an id so we can reference it later
oSelected.style.cursor = 'wait'//until the thing is loaded
oDiv.className = sClassName
oDiv.style.pixelLeft = coords.x + (iBorder * 2)
oDiv.style.pixelTop = (coords.y + coords.h + (iBorder * 2))
XmlHttpPage(sPageName, oDiv, sQuery)
if (fnBeforeAppend) {
fnBeforeAppend(oDiv)
}
oParent.appendChild(oDiv)
oSelected.style.cursor = ''//until the thing is loaded//once it's loaded, set the cursor back
oDiv.style.cursor = ''
}
return oDiv;
}
Position and size the list
function configureSelectList(oDiv, fnOnClick) {
/**************************************************************************************
* Build a dynamic select list and set each of the events for the table elements
* Created in one place and moved to another so that sizing based on the cell width can
* occur without being affected by stylesheet cascades
**************************************************************************************/
if(!fnOnClick) fnOnClick=configureSelectList.clickEvent
if (!oDiv) oDiv = configureSelectList.Container;
var oTable = getDecendant('TABLE', oDiv)
document.getElementsByTagName('TABLE')[0].rows[0].cells[0].appendChild(oDiv)//append to the doc so we are style free, then move it later
if (oTable) {
for (iRow = 0; iRow < oTable.rows.length; iRow++) {
var oRow = oTable.rows[iRow]
oRow.onmouseover = function() { highlightSelection(this) };
oRow.onmouseout = function() { highlightSelection(this) };
oRow.style.cursor = 'hand';
oRow.onclick = function() { closeSelectList(0); fnOnClick ? fnOnClick() : null };
oRow.cells[0].style.whiteSpace = 'nowrap'
}
} else {
//show some kind of error
}
oDiv.style.width = (oTable.offsetWidth + 20) + "px"; //no horiz scroll bars please
oTable.mouseout = function() { closeSelectList(500) };
if (oDiv.firstChild.offsetHeight < oDiv.offsetHeight) oDiv.style.height = oDiv.firstChild.offsetHeight//make sure the list is not too big for a few of items
}
Okay, so - where to start? :) Here is the partial function to begin with, you will need this (now and in the future, if you spend a lot of time hacking JavaScript):
function partial(func /*, 0..n args */) {
var args = Array.prototype.slice.call(arguments, 1);
return function() {
var allArguments = args.concat(Array.prototype.slice.call(arguments));
return func.apply(this, allArguments);
};
}
I see a lot of things about your code that make me cringe, but since I don't have time to really critique it, and you didn't ask for it, I will suggest the following if you want to rid yourself of the hack you are currently using, and a few other things:
The setDynamicSelectElements() function
In this function, you can change this line:
onclick = function() { selectList(ySelectArgs[0], ySelectArgs[1], ySelectArgs[2]) }
To this:
onclick = function() { selectList.apply(null, ySelectArgs); }
The selectList() function
In this function, you can get rid of this code where you are using eval - don't ever use eval unless you have a good reason to do so, it is very risky (go read up on it):
if (fnFollowing) {
fnFollowing = eval(fnFollowing)
configureSelectList.clickEvent = fnFollowing
}
And use this instead:
if(fnFollowing) {
fnFollowing = window[fnFollowing]; //this will find the function in the global scope
}
Then, change this line:
var oDiv = setDiv(sListName, sQuery, 'dynamicSelect', configureSelectList);
To this:
var oDiv = setDiv(sListName, sQuery, 'dynamicSelect', partial(configureSelectListAlternate, fnFollowing));
Now, in that code I provided, I have "configureSelectListAlternate" - that is a function that is the same as "configureSelectList" but has the parameters in the reverse order - if you can reverse the order of the parameters to "configureSelectList" instead, do that, otherwise here is my version:
function configureSelectListAlternate(fnOnClick, oDiv) {
configureSelectList(oDiv, fnOnClick);
}
The configureSelectList() function
In this function, you can eliminate this line:
if(!fnOnClick) fnOnClick=configureSelectList.clickEvent
That isn't needed any longer. Now, I see something I don't understand:
if (!oDiv) oDiv = configureSelectList.Container;
I didn't see you hook that Container property on in any of the other code. Unless you need this line, you should be able to get rid of it.
The setDiv() function can stay the same.
Not too exciting, but you get the idea - your code really could use some cleanup - are you avoiding the use of a library like jQuery or MochiKit for a good reason? It would make your life a lot easier...
A function's properties are not available as variables in the local scope. You must access them as properties. So, within 'fc' you could access 'myvar' in one of two ways:
// #1
arguments.callee.myvar;
// #2
fc.myvar;
Either's fine...
Try inheritance - by passing your whatever object as an argument, you gain access to whatever variables inside, like:
function Obj (iString) { // Base object
this.string = iString;
}
var myObj = new Obj ("text");
function InheritedObj (objInstance) { // Object with Obj vars
this.subObj = objInstance;
}
var myInheritedObj = new InheritedObj (myObj);
var myVar = myInheritedObj.subObj.string;
document.write (myVar);
subObj will take the form of myObj, so you can access the variables inside.
Maybe you are looking for Partial Function Application, or possibly currying?
Here is a quote from a blog post on the difference:
Where partial application takes a function and from it builds a function which takes fewer arguments, currying builds functions which take multiple arguments by composition of functions which each take a single argument.
If possible, it would help us help you if you could simplify your example and/or provide actual JS code instead of pseudocode.

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