Better way of splitting and assigning many values in Javascript? - javascript

I have a for loop that cycles through the number of elements that the user has created. There are a lot of available settings in this plugin, and each element can receive it's specific settings.
User settings are entered in the following format: speed_x: "1000,500 > 1000,200 > 0,0"
This controls the speed_x in/out for 3 separate elements. The > divides by object and the commas separate the in/out.
So I can grab specific object speed_x values, I've split speed_x into speed_x_set (splitting by >) resulting in:
1 1000,500
2 1000,200
3 0,0`
3 Inside the loop, I grab the value by index (since it's the object #) and split it by comma (to get speed_x_in and speed_x_out.)
for(var i=0; i<OS.numberofobjects; ++i){
OS.speed_x_on_set[i]=speed_x_set[i].split(",")[0],
OS.speed_x_off_set[i]=speed_x_set[i].split(",")[1],
...
};
Everything is assigned by object and by setting in/out correctly into the master OS settings object. T*he problem is I have many, many settings which need to be split in this fashion...* for example: delay_x_set, speed_y_set, opacity_set, etc. Their names are all based on the default setting name, with "_set" added as shown above. Hopefully this provides enough information. Thanks!

I would avoid to access to the same item twice and perform the same split twice for each iteration. So, you could have something like:
for (var i = 0, item; item = speed_x_set[i++];) {
var values = item.split(",");
OS.speed_x_on_set.push(values[0]);
OS.speed_x_off_set.push(values[1]);
}
Notice that in JavaScript 1.7 (Firefox) you can simply have:
for (var i = 0, item; item = speed_x_set[i++];) {
var [on, off] = item.split(",");
OS.speed_x_on_set.push(on);
OS.speed_x_off_set.push(off);
}
And hopefully in the next version of ECMAScript as well.
It's called "destructuring assignment".

I would say to cache the split result
for(var objindex=0; objindex<OS.numberofobjects; ++objindex){
var splits = speed_x_set[objindex].split(","); //Cache the split so its does not need to be done twice
OS.speed_x_on_set[objindex] = splits[0];
OS.speed_x_off_set[objindex] = splits[1];
...
};

What you're looking for is called parallel assignment, but unfortunately, JavaScript doesn't have it.
In ruby, however, it is common to see similar patterns:
first, second = "first second".split
As others have noted, the obvious way would be to cache split results and assign them separately. Sorry for not answering your question directly.

Related

InDesign Scripting: Deleting elements from the structure panel

I've imported some XML files inside InDesign (you can see the structure in the picture below) and I've also created a script to get some statistics concerning this hierarchy.
For example, to count the "free" elements:
var items = app.activeDocument.xmlElements.everyItem();
var items1 = items.xmlElements.itemByName("cars");
var cars = items1.xmlElements.everyItem();
var c_free = cars.xmlElements.itemByName("free");
var cars_free = c_free.xmlElements.count().length;
I also have apartments in my structure that's why I'm using itemByName.
The code above returns the correct number of free cars in my structure.
What I'm trying to do - without any luck so far - is to target those free items (inside cars) and either delete all of them or a specific number.
My last attempt was using:
var del1 = myInputGroup2.add ("button", undefined, "Delete All");
del1.onClick = function () {
cars.xmlElements.everyItem().remove();
}
inside a dialog I've created.
Any suggestions will be appreciated cause I'm really stuck here.
I would probably use XPath for this. You can use evaluateXPathExpression to create an array of the elements you want to target. Assuming your root element is cars and it contains elements called cars1, and you want to delete all free elements within a cars1 element, you could do something like:
var myDoc = app.activeDocument;
//xmlElements[0] is your root element, in this case "cars". The xPath expression is evaluated from cars.
//evaluateXPathExpression returns an array of all of the free elements that are children of cars.
var myFrees = myDoc.xmlElements[0].evaluateXPathExpression("cars1/free");
for (var i = myFrees.length - 1; i>=0; i--){
myFrees[i].remove();
}
Tweaking this would require some knowledge of xPath, but it's not terribly hard to learn the basics and it does seem like the simplest approach.
I think your main problem was that XMLElements hasn't a itemByName method. You can only reference XMLElements through their indeces or ids.
Secondly you assume that you got xmlElements from XPath expression but it's likely that you got nothing as your xpath seems uncorrect.
var myFrees = myDoc.xmlElements[0].evaluateXPathExpression("./cars1/free");
var n = myFrees.length;
if ( !n ) {
alert("Aucun élément trouvé");
}
else {
while (n--) myFrees[n].remove();
}
You need to start your expression by setting the origin of your xpath. Here a dot "./" is used to tell you want to look for cars1/free xml elements at the "root" of the xmlelement. Using "//" on the contrary would have returned any cars/free items unregardingly of their locations.

Dynamically making a Javascript array from loop

I know there are a lot of questions about this, but I can't find the solution to my problem and have been on it for a while now. I have two sets of input fields with the same name, one for product codes, and one for product names. These input fields can be taken away and added to the DOM by the user so there can be multiple:
Here is what I have so far, although this saves it so there all the codes are in one array, and all the names in another:
var updatedContent = [];
var varCode = {};
var varName = {};
$('.productVariationWrap.edit input[name="varVariationCode[]"]')
.each(function(i, vali){
varCode[i] = $(this).val();
});
$('.productVariationWrap.edit input[name="varVariationName[]"]')
.each(function(i1, vali1){
varName[i1] = $(this).val();
});
updatedContent.push(varCode);
updatedContent.push(varName);
I am trying to get it so the name and code go into the same array. i.e. the code is the key of the K = V pair?
Basically so I can loop through a final array and have the code and associated name easily accessible.
I can do this in PHP quite easily but no luck in javascript.
EDIT
I want the array to look like:
[
[code1, name1],
[code2, name2],
[code3, name3]
];
So after I can do a loop and for each of the arrays inside the master array, I can do something with the key (code1 for example) and the associated value (name1 for example). Does this make sense? Its kind of like a multi-dimensional array, although some people may argue against the validity of that statement when it comes to Javascript.
I think it's better for you to create an object that way you can access the key/value pairs later without having to loop if you don't want to:
var $codes = $('.productVariationWrap.edit input[name="varVariationCode[]"]'),
$names = $('.productVariationWrap.edit input[name="varVariationName[]"]'),
updatedContent = {};
for (var i = 0, il = $codes.length; i < il; i++) {
updatedContent[$codes.get(i).value] = $names.get(i).value;
}
Now for example, updatedContent.code1 == name1, and you can loop through the object if you want:
for (var k in updatedContent) {
// k == code
// updatedContent[k] == name
}
Using two loops is probably not optimal. It would be better to use a single loop that collected all the items, whether code or name, and then assembled them together.
Another issue: your selectors look a little funny to me. You said that there can be multiple of these controls in the page, but it is not correct for controls to have duplicate names unless they are mutually exclusive radio buttons/checkboxes--unless each pair of inputs is inside its own ancestor <form>? More detail on this would help me provide a better answer.
And a note: in your code you instantiated the varCode and varName variables as objects {}, but then use them like arrays []. Is that what you intended? When I first answered you, i was distracted by the "final output should look like this array" and missed that you wanted key = value pairs in an object. If you really meant what you said about the final result being nested arrays, then, the smallest modification you could make to your code to make it work as is would look like this:
var updatedContent = [];
$('.productVariationWrap.edit input[name="varVariationCode[]"]')
.each(function(i, vali){
updatedContent[i] = [$(this).val()]; //make it an array
});
$('.productVariationWrap.edit input[name="varVariationName[]"]')
.each(function(i1, vali1){
updatedContent[i1].push($(this).val()); //push 2nd value into the array
});
But since you wanted your Code to be unique indexes into the Name values, then we need to use an object instead of an array, with the Code the key the the Name the value:
var updatedContent = {},
w = $('.productVariationWrap.edit'),
codes = w.find('input[name="varVariationCode[]"]'),
names = w.find('input[name="varVariationName[]"]');
for (var i = codes.length - 1; i >= 0; i -= 1) {
updatedContent[codes.get(i).val()] = names.get(i).val();
});
And please note that this will produce an object, and the notation will look like this:
{
'code1': 'name1',
'code2': 'name2',
'code3': 'name3'
};
Now you can use the updatedContent object like so:
var code;
for (code in updatedContent) {
console.log(code, updatedContent[code]); //each code and name pair
}
Last of all, it seems a little brittle to rely on the Code and Name inputs to be returned in the separate jQuery objects in the same order. Some way to be sure you are correlating the right Code with the right Name seems important to me--even if the way you're doing it now works correctly, who's to say a future revision to the page layout wouldn't break something? I simply prefer explicit correlation instead of relying on page element order, but you may not feel the need for such surety.
I don't like the way to solve it with two loops
var updatedContent = []
$('.productVariationWrap.edit').each(function(i, vali){
var $this = $(this)
, tuple = [$this.find('input[name="varVariationCode[]"]').val()
, $this.find('input[name="varVariationName[]"]').val()]
updatedContent.push(tuple)
});

How to reference an array in a function argument

I have a series of arrays that contain words I want to use as text in various HTML divs (there are about 35 of these, I included only a few for brevity).
var bodyplan = ['Anguilliform', 'Compressiform', 'Depressiform', 'Filiform', 'Fusiform', 'Globiform', 'Sagittiform', 'Taeniform'];
var mouthposition = ["Inferior", "Jawless", "Subterminal", "Superior", "Terminal"];
var barbels = ['1', '2', '4 or more'];
var caudalshape = ['Continuous', 'Emarginate', 'Forked', 'Lunate', 'Rounded', 'Truncate'];
I have a switch function that is supposed to change the text based on user selections:
switch(n){
case 1:
changelabels(bodyplan, 8);
break;
case 2:
changelabels(mouthposition, 5);
break;
case 3:
changelabels(barbels, 3);
break;
case 4:
changelabels(caudalshape, 6);
break;
case 5:
changelabels(dorsalspines, 8);
break;
default:
alert("handquestsel error")}};
Finally, I have the function which I would like to make the changes (except it doesn't):
function changelabels(opt1,opt2){
var i = opt2;
var im = opt2 - 1;
var c = 1;
var index = 0;
while (i>=c){
var oldlbl = document.getElementById("rb" + c + "lbl");
var newlbla = opt1.slice(im,i);
var newlblb = opt1.toString();
oldlbl.innerHTML = newlblb;
c = c + 1
index = index + 1
}};
I know the code for my function is just plain wrong at this point, but I have altered it so many times that I'm not sure what's going on anymore. At one point I did have the function able to change the text, but it did so incorrectly (it parsed the name of the array, not extracted a value from the array as I wished). Please help. I know I am overlooking some fundamental concepts here, but am not sure which ones. I've lost count of the hours I've spent trying to figure this out. It's seems like it should be so simple, yet in all my chaotic attempts to make it work, I have yet to stumble on an answer.
EDIT: I want my switch statement to call the function and pass to the function, the appropriate array from which to pull the labels from. The purpose of the app is to help a user learn to identify fish. When the user makes selections on the page, a series of pictures will be shown for various character states with an accompanying label describing the state. For example, when the user selects Mouth Position a series of divs will show the different mouth positions that fish have and have a label below the picture to tell the user what that certain character state is called. I can get the pictures to change just fine, but I am having a hell of a time with the labels.
Why not just something along the lines of:
document.getElementById("bodyplan_label").innerHTML = bodyplan[bodyplan_index];
You seem trying to put everything in really abstract data structures, I see no reason to. Just keep it simple.
Also bodyplan has only 8 elements, so bodyplan[8] will give you an out of bounds exception because arrays start at 0 as is common in all modern programming languages.
If I'm reading your requirement and code correctly, in your switch statement you are passing both a reference to the appropriate array and that array's expected length - you don't need the second parameter because all JavaScript arrays have a .length property.
You don't want to use .slice() to get the individual values out of the array, because that returns a new array copied out of the original - just use arrayVariable[index] to get the individual item at index.
So, putting that together try something like this (with your existing array definitions):
switch(n){
case 1:
changelabels(bodyplan);
break;
case 2:
changelabels(mouthposition);
// etc.
}
function changelabels(data) {
var i,
lbl;
for (i = 0; i < data.length; i++) {
lbl = document.getElementById("rb" + (i+1) + "lbl");
lbl.innerHTML = data[i];
}
}
Notice how much simpler that is than your code? I'm assuming here the elements you are updating have an id in the format "rb1lbl", "rb2lbl", etc, with numbering starting at 1: I'm getting those ids using (i+1) because JavaScript array indexes start at zero. Note also that you don't even need the lbl variable: you could just say document.getElementById("rb" + (i+1) + "lbl").innerHTML = data[i] - however I've left it in so that we have something to expand on below...
Within your function you seem to be changing the labels on a set of elements (radio button labels?), one per value in the array, but you stop when you run out of array items which means any leftover elements will still hold the values from the previous selection (e.g., if the previous selection was "bodyplan" with 8 options and you change to "mouthposition" with only 5 - you probably should hide the 3 leftover elements that would otherwise continue to display the last few "bodyplan" items. One way to do that is instead of setting your loop up based on the array length you could loop over the elements, and if the current element has an index beyond the end of the array hide it, something like this:
function changelabels(data) {
var i,
lbl,
elementCount = 20; // or whatever your element count is
for (i = 0; i < elementCount; i++) {
lbl = document.getElementById("rb" + (i+1) + "lbl");
if (i < data.length) {
lbl.innerHTML = data[i];
lbl.style.display = "";
} else {
lbl.innerHTML = "";
lbl.style.display = "none";
}
}
}
If these elements are labels for radio buttons (just a guess based on the ids) then you'd also want to hide or show the corresponding radio buttons, but I hope you can figure out how to add a couple of lines to the above to do that.
(As mentioned above, be careful about having element ids count up from 1 when the array indexes start at 0.)
If the above doesn't work please post (at least some of) the relevant HTML - obviously I've just had to guess at what it might be like.
SOLUTION: Changed the scope of the array variables to local by moving them into the function where they are used, instead of having them as global variables at the top of the page. I don't understand as I was following every rule of variable declaration. But for some unknown reason, global variables in javascript are abhorrent.
Solution Edit: Found an error in declaring my global variables. This may have been the source of my problem of why I could not access them. But it is a non-issue at this point since I corrected my code.
I don't understand what your trying to achieve exactly with your code. But to pass a variable (in this case an array) by reference you just have to add "&" before the variable.
function the_name(&$var_by_ref, $var_by_value) {
// Here if you modify $var_by_ref this will change the variable passed to the function.
}
More: http://php.net/manual/en/language.references.pass.php
Hope that helps.

Removing items from data bound array

How do I remove an items from a data bound array? My code follows.
for(var i = 0; i < listBox.selectedIndices.length; i++) {
var toRemove = listFiles.selectedIndices[i];
dataArray.splice(toRemove, 1);
}
Thanks in advance!
Edit Here is my swf. The Add Photos works except when you remove items.
http://www.3rdshooter.com/Content/Flash/PhotoUploader.html
Add 3 photos different.
Remove 2nd photo.
Add a different photo.
SWF adds the 2nd photo to the end.
Any ideas on why it would be doing this?
Edit 2 Here is my code
private function OnSelectFileRefList(e:Event):void
{
Alert.show('addstart:' + arrayQueue.length);
for each (var f:FileReference in fileRefList.fileList)
{
var lid:ListItemData = new ListItemData();
lid.fileRef = f;
arrayQueue[arrayQueue.length]=lid;
}
Alert.show('addcomplete:' + arrayQueue.length);
listFiles.executeBindings();
Alert.show(ListItemData(arrayQueue[arrayQueue.length-1]).fileRef.name);
PushStatus('Added ' + fileRefList.fileList.length.toString() + ' photo(s) to queue!');
fileRefList.fileList.length = 0;
buttonUpload.enabled = (arrayQueue.length > 0);
}
private function OnButtonRemoveClicked(e:Event):void
{
for(var i:Number = 0; i < listFiles.selectedIndices.length; i++) {
var toRemove:Number = listFiles.selectedIndices[i];
//Alert.show(toRemove.toString());
arrayQueue.splice(toRemove, 1);
}
listFiles.executeBindings();
Alert.show('removecomplete:' + arrayQueue.length);
PushStatus('Removed photos from queue.');
buttonRemove.enabled = (listFiles.selectedItems.length > 0);
buttonUpload.enabled = (arrayQueue.length > 0);
}
It would definitely be helpful to know two things:
Which version of ActionScript are you targeting?
Judging from the behavior of your application, the error isn't occurring when the user removes an item from the list of files to upload. Looks more like an issue with your logic when a user adds a new item to the list. Any chance you could post that code as well?
UPDATE:
Instead of: arrayQueue[arrayQueue.length]=lid
Try: arrayQueue.push(lid)
That will add a new item to the end of the array and push the item in to that spot.
UPDATE 2:
Ok, did a little more digging. Turns out that the fileList doesn't get cleared every time the dialog is opened (if you're not creating a new instance of the FileReferenceList each time the user selects new files). You need to call splice() on the fileList after you add each file to your Array.
Try something like this in your AddFile() method...
for(var j:int=0; j < fileRefList.fileList.length; j++)
{
arrayQueue.push(fileRefList.fileList[j]);
fileRefList.fileList.splice(j, 1);
}
That will keep the fileList up to date rather than holding on to previous selections.
I see one issue. The selected indices are no longer valid once you have spliced out the first element from the array. But that should only be a problem when removing multiple items at once.
I think we need to see more code about how you are handling the upload before we can figure out what is going on. It looks to me like you are holding a reference to the removed FileReference or something. The described problem is occurring when you upload a new file, not when you remove the selected one.
Do you mean to use listBox and listFiles to refer to the same thing?
I'm stepping out on a limb here, because I don't have a ton of experience with JavaScript, but I'd do this the same way that I'd do it in C, C++, or Java: By copying the remaining array elements down into their new locations.
Assuming that listFiles.selectedIndices is sorted (and its contents are valid indices for dataArray), the code would be something like the following:
(WARNING: untested code follows.)
// Don't bother copying any elements below the first selected element.
var writeIndex = listFiles.selectedIndices[0];
var readIndex = listFiles.selectedIndices[0] + 1;
var selectionIndex = 1;
while(writeIndex < (dataArray.length - listFiles.selectedIndices.length)) {
if (selectionIndex < listFiles.selectedIndices.length) {
// If the read pointer is currently at a selected element,
// then bump it up until it's past selected range.
while(selectionIndex < listFiles.selectedIndices.length &&
readIndex == listFiles.selectedIndices[selectionIndex]) {
selectionIndex++;
readIndex++;
}
}
dataArray[writeIndex++] = dataArray[readIndex++];
}
// Remove the tail of the dataArray
if (writeIndex < dataArray.length) {
dataArray.splice(writeIndex, dataArray.length - writeIndex);
}
EDIT 2009/04/04: Your Remove algorithm still suffers from the flaw that as you remove items in listFiles.selectedIndices, you break the correspondence between the indices in arrayQueue and those in listFiles.selectedIndices.
To see this, try adding 3 files, then doing "Select All" and then hit Remove. It will start by removing the 1st file in the list (index 0). Now what had been the 2nd and 3rd files in the list are at indices 0 and 1. The next value taken from listFiles.selectedIndices is 1 -- but now, what had been the 3rd file is at index 1. So the former File #3 gets spliced out of the array, leaving the former 2nd file un-removed and at index 0. (Using more files, you'll see that this implementation only removes every other file in the array.)
This is why my JavaScript code (above) uses a readIndex and a writeIndex to copy the entries in the array, skipping the readIndex over the indices that are to be deleted. This algorithm avoids the problem of losing correspondence between the array indices. (It does need to be coded carefully to guard against various edge conditions.) I tried some JavaScript code similar to what I wrote above; it worked for me.
I suspect that the problem in your original test case (removing the 2nd file, then adding another) is analogous. Since you've only shown part of your code, I can't tell whether the array indices and the data in listFiles.selectedIndices, arrayQueue, and fileRefList.fileList are always going to match up appropriately. (But I suspect that the problem is that they don't.)
BTW, even if you fix the problem with using splice() by adjusting the array index values appropriately, it's still an O(N2) algorithm in the general case. The array copy algorithm is O(N).
I'd really need to see the whole class to provide a difinitive answer, but I would write a method to handle removing multiple objects from the dataProvider and perhaps assigning a new array as the dataProvider for the list instead of toying with binding and using the same list for the duration. Like I said, this is probably inefficient, and would require a look at the context of the question, but that is what I would do 9unless you have a big need for binding in this circumstance)
/**
* Returns a new Array with the selected objects removed
*/
private function removeSelected(selectedItems:Array):Array
{
var returnArray:Array = []
for each(var object:Object in this.arrayQueue)
{
if( selectedItems.indexOf(object)==-1 )
returnArray.push( object )
}
return returnArray;
}
You might be interested in this blog entry about the fact that robust iterators are missing in the Java language.
The programming language, you mentioned Javascript, is not the issue, it's the concept of robust iterators that I wanted to point out (the paper actually is about C++ as the programming language).
The [research document]() about providing robust iterators for the ET++ C++ framework may still e helpful in solving your problem. I am sure the document can provide you with the necessary ideas how to approach your problem.

fastest way to detect if a value is in a group of values in Javascript

I have a group of strings in Javascript and I need to write a function that detects if another specific string belongs to this group or not.
What is the fastest way to achieve this? Is it alright to put the group of values into an array, and then write a function that searches through the array?
I think if I keep the values sorted and do a binary search, it should work fast enough. Or is there some other smart way of doing this, which can work faster?
Use a hash table, and do this:
// Initialise the set
mySet = {};
// Add to the set
mySet["some string value"] = true;
...
// Test if a value is in the set:
if (testValue in mySet) {
alert(testValue + " is in the set");
} else {
alert(testValue + " is not in the set");
}
You can use an object like so:
// prepare a mock-up object
setOfValues = {};
for (var i = 0; i < 100; i++)
setOfValues["example value " + i] = true;
// check for existence
if (setOfValues["example value 99"]); // true
if (setOfValues["example value 101"]); // undefined, essentially: false
This takes advantage of the fact that objects are implemented as associative arrays. How fast that is depends on your data and the JavaScript engine implementation, but you can do some performance testing easily to compare against other variants of doing it.
If a value can occur more than once in your set and the "how often" is important to you, you can also use an incrementing number in place of the boolean I used for my example.
A comment to the above mentioned hash solutions.
Actually the {} creates an object (also mentioned above) which can lead to some side-effects.
One of them is that your "hash" is already pre-populated with the default object methods.
So "toString" in setOfValues will be true (at least in Firefox).
You can prepend another character e.g. "." to your strings to work around this problem or use the Hash object provided by the "prototype" library.
Stumbled across this and realized the answers are out of date. In this day and age, you should not be implementing sets using hashtables except in corner cases. You should use sets.
For example:
> let set = new Set();
> set.add('red')
> set.has('red')
true
> set.delete('red')
true
> set.has('red')
false
Refer to this SO post for more examples and discussion: Ways to create a Set in JavaScript?
A possible way, particularly efficient if the set is immutable, but is still usable with a variable set:
var haystack = "monday tuesday wednesday thursday friday saturday sunday";
var needle = "Friday";
if (haystack.indexOf(needle.toLowerCase()) >= 0) alert("Found!");
Of course, you might need to change the separator depending on the strings you have to put there...
A more robust variant can include bounds to ensure neither "day wed" nor "day" can match positively:
var haystack = "!monday!tuesday!wednesday!thursday!friday!saturday!sunday!";
var needle = "Friday";
if (haystack.indexOf('!' + needle.toLowerCase() + '!') >= 0) alert("Found!");
Might be not needed if the input is sure (eg. out of database, etc.).
I used that in a Greasemonkey script, with the advantage of using the haystack directly out of GM's storage.
Using a hash table might be a quicker option.
Whatever option you go for its definitely worth testing out its performance against the alternatives you consider.
Depends on how much values there are.
If there are a few values (less than 10 to 50), searching through the array may be ok. A hash table might be overkill.
If you have lots of values, a hash table is the best option. It requires less work than sorting the values and doing a binary search.
I know it is an old post. But to detect if a value is in a set of values we can manipulate through array indexOf() which searches and detects the present of the value
var myString="this is my large string set";
var myStr=myString.split(' ');
console.log('myStr contains "my" = '+ (myStr.indexOf('my')>=0));
console.log('myStr contains "your" = '+ (myStr.indexOf('your')>=0));
console.log('integer example : [1, 2, 5, 3] contains 5 = '+ ([1, 2, 5, 3].indexOf(5)>=0));
You can use ES6 includes.
var string = "The quick brown fox jumps over the lazy dog.",
substring = "lazy dog";
console.log(string.includes(substring));

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