I have a map element that has multiple areas, and user can select one of those. Each area has an ID that represents a number (which I need to use in an equation later on).
How do I store the ID of selected area in a variable for later use?
My work so far:
function areaSelection(){
$("map").on('click', 'area', function (e){
e.preventDefault();
var areaSelect = parseInt(this.id);
console.log(areaSelect);
});
}
var mapSelection = areaSelection();
$("area").on('click', areaSelection);
Do your best to never use global variables.
Firstly, you're assigning a function call to a variable, which is returning undefined (all functions do this unless the return statement is used).
Secondly, the areaSelection function only creates the click event.
It doesn't actually calculate the areaSelect value.
Instead try something like this:
var mapSelection;
$("map").on('click', 'area', areaSelection);
function areaSelection(e) {
e.preventDefault();
mapSelection = parseInt(this.id);
}
This way, the mapSelection is getting set any time the map is clicked, but be aware that this is not likely to be efficient.
Related
I'm a noob and also new to this site, so let me know if there are things I should do to improve this post. Anyway, I have a function that is re-used frequently in my site, so I stored it in a global variable and want to call it when a certain button is clicked.
The code looks like this (see below). My problem is that although I can confirm that the button click tries to call the function, it is clearly never actually called (none of my alerts fire and the changes to the text fields are not saved). All of this is contained in the $(document).read(function...
Have I made a dumb mistake somewhere, or is there something I'm doing clearly wrong?
$(document).ready(function () {
//Description:
//Global wrapper variable that contains all global functions. These include:
// 1. saveAll: Saves all values not stored in session data to hidden fields - this includes
// all added ingredient information. This allows us to manually pass values between
// client and server to save to db and also means we can eliminate Null values in table
// storage using a manual delimiter.
//----------------------------------------------------------------------------------------------
var Global = (function () {
return {
saveAll: function () {
alert("entering save");
//start by creating an array and initializing the length of the for loop
var saveValues = [];
var numVals = $('#HidRowCt').val();
alert("numVals: " + numVals);
//Now loop through each ingredient row and create a string containing all textbox values
//in this case, we'll do so by creating an array and then combining the values with a custom delimiter
//the strings will then be saved, one by one, into the saveValues array, which will be serialized as a JSON object,
//stored in a hidden field, and passed to the server
for (i = 1; i < numVals; i++) {
var TxtIngName = $('#TxtIngName' + i).val();
var TxtIngNumUnits = $('#TxtIngNumUnits' + i).val();
var SelIngUnits = $('#SelIngUnits' + i).val();
//make temporary array and string
var saveArr = new Array(TxtIngName, TxtIngNumUnits, SelIngUnits);
var saveStr = saveArr.join("-||-");
saveValues.push(saveStr);
}
alert("Save Values: " + saveValues);
//this will automatically escape quotes, delimited with ","
var jsoncvt = JSON.stringify(saveValues);
$("#HidSave").val(jsoncvt);
}
};
});
//----------------------------------------------------------------------------------------------
//Description:
//Hijack the click event for the save button. Saves values not saved in session data.
//
//Functions:
// Global.saveAll()
//----------------------------------------------------------------------------------------------
$("#SaveChanges").data.clickEvent = $("#SaveChanges").attr('onClick'); //save onclick event locally
$("#SaveChanges").removeAttr('onClick'); //and remove the onclick event
$('#SaveChanges').on('click', function (event) {
Global.saveAll();
//eval($("#SaveChanges").data.clickEvent); //now go ahead with the click event
});
Well, I never figured out why this didn't work, but....
I just removed the global variable and created a separate function for saveAll() and it works. Interestingly, I have a second application using the same code that uses the Global.saveAll (with the same innards) and works fine, so I must have something unusual in one of my earlier lines.
Thanks for your suggestions!
Try setting window.Global = ..., since declaring var Global sets the scope to be within the ready closure.
Then you should be able to use it later.
I just removed the global variable and created a separate function for saveAll() and it works.
I've got a two-part question.
One: can I use the last variable I set to update the value on the line after if (!last) {? i.e., something like last = size;?
var j$ = jQuery.noConflict();
function updateCount() {
var self = j$(this),
last = self.data('last'),
size = self.val().length,
span = j$('.currentCount');
if (!last) {
self.data('last', size);
} else if (last != size) {
span.text(size);
self.data('last', size);
}
}
j$('textarea[id$=textBody]').on('propertychange change click keyup input paste', updateCount);
Secondly, can I chain my .on('propertychange ... line to have updateCount run as soon as the script is loaded?
Question 1:
No, you can not use simply the assignment to the variable because there is no data-binding in jQuery. So updating last variable will never update the data-last of the jQuery object.
Question 2:
This is what I am used to do:
j$('textarea[id$=textBody]').on('propertychange change ...', updateCount).change();
Where change() automatically triggers the function.
For Q1: No you can't. If you want data binding to work, you can try AngularJS where 2 way data binding between UI and model is possible.
Q2: My solution would be something like this using immediate function
$('textarea[id$=textBody]').on('propertychange change click keyup input paste', (function(){
updateCount();
return updateCount;
}()));
The last variable has a copy of the value in self.data('last'), it is not a pointer, so you would have to do something like this:
last = size;
self.data('last', last);
For the second question, you can trigger the event or just call the function:
j$('textarea[id$=textBody]').trigger('propertychange');
// or
j$('textarea[id$=textBody]').each(updateCount);
function showHideSoldTo() {
if ($("#radio-text-sold-to").prop("checked")) {
$("#select-sold-to").hide();
$("#text-sold-to").show();
} else if ($("#radio-select-sold-to").prop("checked")) {
$("#text-sold-to").hide();
$("#select-sold-to").show();
}
}
$("#radio-text-sold-to").click(showHideSoldTo());
$("#radio-select-sold-to").click(showHideSoldTo());
All this is inside a document ready wrapper.
Remove the () from the function names in the click call. So..
$("#radio-text-sold-to").click(showHideSoldTo);
...
Remove the () from the function names in the click call
just try like
$("#radio-text-sold-to").click(showHideSoldTo);
$("#radio-select-sold-to").click(showHideSoldTo);
The problem is with the value you pass to the .click() method it's supposed to be a function value but instead you are invoking the function and as a result passing the return value of that function (which is equal to undefined)
the fix is simple you need to remove the () in these two lines
$("#radio-text-sold-to").click(showHideSoldTo());
$("#radio-select-sold-to").click(showHideSoldTo());
So they become
$("#radio-text-sold-to").click(showHideSoldTo);
$("#radio-select-sold-to").click(showHideSoldTo);
in javascript any identifier identifies a value. That value might be a simple value such as an integer or it might be a more complex object and as is the case with the value you pass as a callback or event handler it might be a function value.
These two lines of code are basically the same
function myFoo() {}
var myFoo = function() {}
and in the latter it's explicit that the right hand side is assigned to the left hand side. Ie that the function value is assigned to an identifier.
I want to add data variables to an element before causing a specific behavior, but this may require adding more than one data parameter. How can I accomplish this?
$("#dlg_box").data("r_redirect","index.php").dialog("open");
You can do it like this:
var data = $("#dlg_box").data();
data.r_redirect = "index.php";
data.foo = "bar";
$("#dlg_box").dialog("open");
This was taken from here.
To retrieve your values:
$("#dlg_box").data("r_redirect");
$("#dlg_box").data("foo");
JQuery's data() method also takes an JS Object as a parameter. So you might think of passing {"r_redirect": "index.php", "whatEver": "youWant" ...} etc to pass multiple values match your requirement.
Ultimately, the data() method converts your parameters into an Object. So whether you pass an Object or Key and Value separately should not matter
There are different ways to attach data to a jQuery dialog. If you need to attach multiple Data, I recomend using .data("myData", { /* OBJECT */ }, however you can also use inline string and array data. As far as why yours won't work, with so little code to go on, it could be numerous things. However, I've attached a working example of a Dialog with "params" or data for you to take example from. If you post more of your header code tho, I have a feeling we might find a syntax error or a lack of "doc ready" included. Just some thoughts. Anyway, my example:
jsFiddle
$(function() {
// Set the dialog to not open on load and clear all changes made when closed
$("#dlg").dialog({
autoOpen: false,
modal: true,
close: function(e) {
$(this).children("input").nextAll("p").remove();
}
}) // next i call for my first inner button which will show you how to get "attached" data
.children("#attached").on("click", function(e) {
var dlgData = $("#dlg").data("myData");
$(this).after($("<p />").text(dlgData.data1 + " " + dlgData.data2));
}) // finally, the button that will get the string data that was added in the HTML
.next("#inline").on("click", function(e) {
var dlgData = $("#dlg").data("inline");
$(this).after($("<p />").text(dlgData));
});
// simply open our dialog
$("button").on("click", function(e) {
// HERE data is ATTCHED to our dialog just before opening
$("#dlg").data("myData", { data1: "Hello", data2: "world" }).dialog("open")
});
});
$('#Dialog').data('data1', data1).data('data2', data2).dialog('open');
While Initializing the dialog get the values following:
var data1 = $(this).data('data1');
var data2 = $(this).data('data2');
There are some rules you should be aware of before using this!
ADDING
Adding variables using the object returned from $('.selector').data() works because the data object passes by reference, so anywhere you add a property, it gets added. If you call data() on another element, it gets changed. It is what it is what it is...
Adding an object places a object inside of the data object, as well as "extends the data previously stored with that element." - http://api.jquery.com/data/#entry-longdesc
That means that adding an obj to dataObj becomes
dataObj === { /*previous data*/, obj : { } }
Adding an array does not extend the data previously stored, but doesn't behave the same as a simple value either...
USING
If you have simple values stored, you can place them into variables and do what you want with them without changing the data object.
however
if you are using an object or array to store data on an element, beware!
Just because you store it to a variable does not mean you are not changing data value.
Just because you pass it to a function does not mean you are not changing data values!
It is what it is what it is.. unless it's simple.. then it's just a copy. :p
var data = $("#id").data(); // Get a reference to the data object
data.r_redirect = "index.php"; // Add a string value
data.num = 0; // Add a integer value
data.arr = [0,1,2]; // Add an array
data.obj = { a : "b" }; // Add an object
// but here is where the fun starts!
var r_redirectString = data.r_redirect; // returns "index.php", as expected.. cool
r_redirectString = "changed" // change the value and the compare :
data.r_redirect == r_redirectString // returns false, the values are different
var oArr = data.arr; // Now lets copy this array
oArr.push(3); // and modify it.
data.arr == oArr // should be false? Nope. returns true.
// arrays are passed by reference.
// but..
var oObj = data.obj // what about objects?
oObj["key"] = "value"; // modify the variable and
data.obj["key"] == oObj["key"] // it returns true, too!
So, resources..
What's the best way to store multiple values for jQuery's $.data()?
https://stackoverflow.com/a/5759883/1257652
Below is my code fragment:
<div onclick = "myClick('value 1')">
button 1
</div>
<div onclick = "myClick('value 2')">
button 2
</div>
Basically when I for each click on a different div, a different value will be passed to the JavaScript function.
My Question is how can I keep track of the value passed in the previous click?
For example, I click "button 1", and "value 1" will be passed to the function. Later, I click on "button 2", I want to be able to know whether I have clicked "button 1" before and get "value 1".
Just add it to a variable in your script:
var lastClicked;
var myClick = function(value) {
lastClicked = value;
};
You can define somekind of variable, like var lastUsed;
add additional line to your function:
var lastUsed = null;
function myClick(value){
prevClicked = lastUsed; //get the last saved value
...
lastUsed = value; //update the saved value to the new value
...
}
And here you go
You need a variable. Variables are like little boxes in which you can store values. In this case, we can store the value that was last passed to the function myClick.
In Javascript, you can define a variable like this:
var lastClickedValue;
You can "put" a value into that variable. Let's say you want to put your name in there. You would do this:
lastClickedValue = 'sams5817';
Now here's the tricky bit. Variables have "scope". You might want to think about it as their "life-time". When a variable reaches the end of its scope, you cannot read or write to it anymore. It's as if it's never been. Functions define a scope. So any variable you define in a function will disappear at the end of the function. For example:
function myClick(value)
{
var lastClickedValue;
alert('lastClickedValue is = ' + value);
lastClickedValue = value;
}
That looks almost right, doesn't it? We declared a variable, display its last value, and update it with the new value.
However, since the lastClickedValue was declared in the function myClick, once we've reached the end of that function, it's gone. So the next time we call myClick, lastClickedValue will be create all over again. It will be empty. We call that an "uninitialized" variable.
So what's the problem? We're trying to remember a value even after the end of myClick. But we declared lastClickedValue inside myClick, so it stops existing at the end of myClick.
The solution is to make sure that lastClickedValue continues to exist after myClick is done.
So we must delcare lastClickedValue in a different scope. Luckily, there's a larger scope called the "global scope". It exists from the moment your page loads, and until the user moves on to another webpage. So let's do it this way:
var lastClickedValue;
function myClick(value)
{
alert('lastClickedValue is = ' + value);
lastClickedValue = value;
}
It's a very small difference. We moved the declaration of the variable lastClickedValue to be outside the function myClick. Since it's outside, it will keep existing after myClick is done. Which means that each time we call myClick, then lastClickedValue will still be there.
This will let you know what the last value passed to myClick was.
Finally, I'd like to advise you to look for some kind of Javascript tutorials. I wish I knew of some good ones to recommend, but I'm certain you can find a few on the Internet. If you try to write programs before understanding what you're doing, you'll find yourself producing work that is less than what you're capable of. Good luck!
I suppose you need something like this
var clickedButtons = [];
function myClick(value){
...
clickedButtons.push(value);
...
}
I am surprised that no one else mentioned this, but since functions are first class objects in JavaScript, you can also assign attributes and methods to functions. So in order to remember a value between function calls you can do something like I have with this function here:
function toggleHelpDialog() {
if (typeof toggleHelpDialog.status === 'undefined')
toggleHelpDialog.status = true;
else
toggleHelpDialog.status = !toggleHelpDialog.status;
var layer = this.getLayer();
if (toggleHelpDialog.status) layer.add(helpDialog);
else helpDialog.remove();
layer.draw();
}
Here I have added an attribute named 'status' to the toggleHelpDialog function. This value is associated with the function itself and has the same scope as the toggleHelpDialog function. Values stored in the status attribute will persist over multiple calls to the function. Careful though, as it can be accessed by other code and inadvertently changed.
we can leverage javascript static variables
One interesting aspect of the nature of functions as objects is that you can create static
variables. A static variable is a variable in a functionâs local scope whose value persists across
function invocations. Creating a static variable in JavaScript is achieved by adding an instance
property to the function in question. For example, consider the code here that defines a function
doSum that adds two numbers and keeps a running sum:
function doSum(x,y){
if (typeof doSum.static==='undefined'){
doSum.static = x+y;
}else{
doSum.static += x+y;
}
if (doSum.static >= 100){doSum.static = 0;doSum.static += x+y;}
return doSum.static;
}
alert(doSum(5,15))
alert(doSum(10,10))
alert(doSum(10,30))
alert(doSum(20,30))